There's a lot to get through here, so it's going to be difficult to stay on a standard track of thought here - so at times you may have to bear with me. I'll run through methods and scenarios that we are/can be tracked by the government, corporate interests, skip tracers, and ethical hackers (the white-hats are not your friend, I'll explain later).
First of all, this isn't to spread paranoia. Looking over your shoulder at all times is an unhealthy practice, of which most of us do not need to do. However, if you are a dissident, or have differing opinions that the government does and how you use your rights, you may want to take a few basic precautions, as the older this parasitic country gets, the more individualism will be criminalized. A sad reality is that political dissidence and activism for human rights are, according to the federal government, strong markers for domestic terrorism. It's a pre-emptive strike against uprising, which works in their favor.
Here's how to get on the radar. With systems like TrapWire, the Next Generation Identification system et all, even if you never speak to anyone in your whole life, the way you carry yourself and act may mark you as a terrorist. For instance, if you were to do anything that would be similar to what people do before comitting a crime, or perhaps doing something (passive or not) that sticks you out of a crowd like a sore thumb. Ventures into privacy, like avoiding cameras, could also mark you. In this case, you may be tracked across the network of cameras for total surveillance. There are cameras everywhere these days. Webcams and IP cameras especially, are the easiest to access. We have them everywhere. Access to these cameras is as simple as typing a url into any browser, or by using a virus or botnet to root commands straight into your system, which may include webcam access. As the internet uses up the last remaining IPv4 addresses (you might recognize 220.127.116.11 as a common address), the IPv6 protocol provides native support for desktop sharing and network access. These addresses use very different addresses, in hexadecimal instead of decimal. They will look like 2001:db8:85a3:0:0:8a2e:370:7334.
Assuming you do more than look shifty, there's some other things you can do. Being too public about your opinions can land you quickly in hot water - you might find this out if you try and cross the border and are denied because you're on a no-fly list or terrorist database. These things happen for really obscure reasons too. If somebody really hated you, they could submit a tip to the FBI that you're making a bomb, and you better believe you'll make some lists right away. If you really want to find out what's in your file, have somebody else submit a Freedom Of Information Act request. It has to be somebody else. They are legally required to show the stuff to you, although they may redact large portions of the file to the point of being hilarious. One such file would be the FBI domestic terrorist slideshow that was recovered detailing anarchists as terrorists, making many generalizations, and pronouncing really stupid things. At least, that's what you could read between the black lines, which were even drawn in places over google clipart.
You might also be in the wrong place at the wrong time. Like getting accidentally stuck in a picture with anarchists smashing the state. Or perhaps a bit too close to Greenpeace building climbers. Get too close to the heat, and the feds will come back to burn you. Even if you are innocent, if the case builds then you might get a subpeona shoved in your hands for a grand jury (which is neither grand or a fair jury). In these situations, you need to take precautions. Even if you don't agree with the agenda of freedom fighters and eco-warriors, if you plan to intereact with them on any level, be aware that that interaction can mark you - you may not care, and that's fine. Otherwise, take the cues from them. Bandanna masks are more than a solidarity statement.
Things you say online can mark you as well. Facebook has a algorithm set up that logs keywords and specific phrases, one that turns out low volumes of content, but it has almost zero false reporting. These logs are most assuredly handed to police forces and can be key pieces of evidence. This means 3 things. One, get off facebook. It's bad, and you should feel bad. Two, don't set up accounts in your name or with your identification. It's really not hard to make anonymous accounts, and you can still play digital junkee with people you trust versus open access. Three, your digital presence is more obvious to a skilled eye than if you were sucking air in the next room, even. That is something you must work on, or watch your rights get thrown out with consequences.
Now let's assume that you got on the FBI's radar, and they want you bad. That means they called you a terrorist, so they can literally do anything they want with you. Because there is no set definition of a terrorist, anybody can be a terrorist at any time. It's kind of like a childish namecalling thing - big meanie stupidhead. Except in the wake of 9/11 everybody got so blindly overpatriotic that we threw our hands in so that we can turn "terrorism" into a official denunciation of humanity. It's something we nowadays do abroad and each other. Such as now. All I have to say - YOLO (you only live once). If we're terrorists, lets just own it and get on with life. If it really brings you down, you could always commit.... anywho...
The first thing they will do is probably check out your facebook (DELETE YOUR FACEBOOK), because most people do not have privacy settings enabled, or care about privacy, so everything is public all the way down to the last time you tweeted about your morning shit (DELETE TWITTER). If that isn't enough, they might check Google+ (QUIT GOOGLING) because if you have an email account, you also have a public-defaulted Google+ profile, among other google accounts which are automatically created, such as Google Places, Google Now, and Google Maps - all which use your logins and phone location to actively track you, even determining where you live, where you work, and your favorite places to hang out. Those things are almost always public by default, and all you need is a username, perhaps even a simple name, to go look all this stuff up.
Now for the internet, computers. If they know you're name or SSN, they can run a simple check with Internet Service Providers, who are legally required to turn over all they have on you. This means logs of everything you've done, went, and when. This also provides them with the first of many ways they can figure out your financial affairs. Banks nowadays like to get SSN's from everyone, which is the easiest way to check out your bank info, but after that, the next easiest marker is to look what you connected your bills to. They can determine your location based on where you buy things, where you frequent, where you live, what you buy and do, etc. With the cooperation between the government and your ISP, nothing you do online will be totally safe. Common proxies that people use only proxy after they send, so that only the very last route to where you want to go is anonymized.
Without any protection, government can take total control over your network if it is open. They could do nearly anything at that point. They can also hack in if they so choose, and keep going. If getting in electronically is too hard, then they can (and have in the past) made entry into places to wire many types of devices for total surveillance, and then back out. I remember seeing a few photos of where and how they did it, it's hilarious how sneaky they are about getting through walls where people put stuff against it, totally making it impossible to see unless you really went hunting for it.
If they have issues getting a simple screen grab together, they can use TEMPEST. TEMPEST uses the signals that are emitted from LCD screens, etc. to recreate a signal based off of the radiation given off - at a range of up to 100 feet. This takes absolutely no other hacking to do - you're literally just picking up the signal and going.
Assuming you don't do a full body check for GPS trackers on your car everyday, they don't even need to tail you to figure out where you're going.
If you happen to have windows where you live (like most people do) then they can also use laser microphones from a distance to listen in on whatever conversation is happening inside, without being visible or without causing alarm.
With this, I cannot stress enough that the idea of getting a search warrant to go through your house is the least productive way to put you under surveillance. In a digital age, it is easier to track you from outside, and in the public domain, than it is to knock on your door. In fact, if you ever meet a fed with a badge, you can rest assured that they already know more about you than you do. Physical contact means that people will be alarmed and start covering their tracks or altering behavior - so by public and outside observation, they can pinhole you with your own help. DELETE YOUR FUCKING FACEBOOK!
Now... here's some ways you can prevent all this surveillance.
When it comes to cameras, you can do three things. You can knock the fuckers off the wall, you can track them to avoid them, or you can alter your appearance, speech, and mannerisms so that you on camera looks and sounds nothing like the real you. I think knocking the fuckers off the wall is probably the easiest. It's really odd to go camera hunting every room you go in, and I am not a famous actor, so I'd rather not pretend to be. Makeup, glasses, hats, and other clothing that hides your body is good. The more, the better. If you have identifying marks, those are probably the first things you want to cover. In a black bloc, for instance, the idiot running around with the phoenix tattoo is going to be written down as "male with phoenix tattoo, right calf". That's damnation already. Make camera killing a group activity, make it a local past time, make it a national sport. The more people, the better. All the systems are bullshit if none of them can actually run.
With your phone, it can be more tricky. Your network will always hand you over, no matter what size. So, if you can use prepaid phones without GPS and use cash with anonymous information, then you might be able to pull it off. As for smartphones, Android is much more secure than the competitors. You can download TextSecure that encrypts your texts in a secure on-phone area so that they cannot be read after the fact (such as by using Cellbrite), and also supports full PGP communication between two TextSecure users who share their public cryptography keys in a key pairing session (which cannot be intercepted, and they both retain their private keys). You can also download the Project Guardian applications: Orbot + Tor which anonymizes browsing the internet as long as you use the Tor browser, or can anonymize the entire device if your phone is rooted. PG also has a camera application to anonymize faces in pictures, as well as a chat platform that will help you in supporting encrypted, leave-no-trace text chatting. There is also a plethora of anti-GPS apps, which will spoof the active GPS for you, so that it is much more difficult to track your GPS as it will be broadcast only as from the place you select (Kathmandu, perhaps?). The less your battery is in your phone, the better. While many phones, just like computers, have batteries to keep the phone partially turned on while the battery is discharged, removing the battery prevents the phone from fully turning on, and if GPS works when the battery is out, it will be very limited.
DELETE YOUR GODDAMN FACEBOOK. Social networking was a great idea, but the implications of a globalised public network like that are staggering boons to oppressive governments and white-hate hackers. Remove photos. Pinterest might be okay if you don't post your own pics, due to the fact that it explodes the intellectual mind in a flurry of cakes and wedding dresses. Obviously, I don't like Pinterest. But then, I don't like any social network. They're all inherently insecure - they rely that you simply trust your information to someone, and simply trust that your friends won't turn you over if you ever happen to go rogue. Explore all your accounts to either delete or anonymize your presence. Frequently google yourself and your profiles as a public bystander to properly visualize just how open you are with the world. I would rather you be a grumpy shut-in and plot great things, than be a bursting socialite under the watchful eye of uncle sam the rapist.
When it comes to TEMPEST, LED monitors emit much less radiation, and you probably won't be tracked with it. If you still have CRT or LCD monitors, use them in a central place in the house (preferably surrounded by metal things, or a Faraday cage), and then monitoring devices will be out of range for passive surveillance.
If you worry about your conversations being heard from the windows, you can always buy a jammer that will emit a high pitched frequency which drowns out their devices, or for a cheaper solution, throw a dildo app on your phone and lean it up against the window so it vibrates the whole thing. All they will hear is the sounds of the rumbling rattle.
You can also set up your own private GSM network, to completely avoid using mobile phone carriers, and secure your communications - however this can be expensive and takes a lot of technical radio skill and linux mastery. It's possible, but not easy.
On your computer, you'd be better off with Linux - it's much more secure. Much faster and more efficient as well. There aren't any viruses for linux and if you use good add-on firewalls to what's already there, you can really make it impenetrable wirelessly. Physical tapping is always a threat, so you just have to watch for signs of entry or things that have been randomly added, like usb drives, dongles, cords, etc. The best operating system for anonymity is called Tails, and it runs entirely off of a CD, USB, or virtual image (not recommended). It runs everything you do through proxy and then when you're all done with it, it forgets every single thing you did in the session (amnesiac) so that data forensics is useless. It makes you a ghost. Combine it with a Virtual Private Network, such as iPredator, and you can be fully encrypted in both directions, insomuch as to even be invisible to your ISP. What you should use for an internet browser is called "Tor". Tor runs off a modified version of Firefox which is preset with the right settings and add-ons so that when you use it, your connections will be bounced around so much that nobody will be able to figure out where it came from. Using VPN's and decent proxies slows down the internet for you, because connections can be routed far away and cause lag - however, that's what makes them so secure. Tor also has a version called obsproxy (something like that) which is regular tor but vamped up to help circumvent censorship and suppression by ISP's. Always make sure Tails and Tor are up-to-date. Get into the habit of using new IP's from them regularly. Between sites, even. This can make tracking what you do online impossible to track. The biggest weak link with internet anonymity, if you are otherwise secured, is you. If you are all secure, and then give your private info to somebody, all the security was a moot point, because you provided the exact thing the stuff was meant to guard you from. You might have to change a lot of habits, but that's just the nature of the beast.
People often disassociate the underground with themselves. That the underground is some ephemeral blob of hackers and rebels... but this is simply not true. It's much more broad, much less organized. If the underground were to organize, they would no longer be the underground... organization is an above-ground thing. And the real underground is all types of people. Every color, age, race, nationality, unnationality, etc. Vegans, cannibals, omnivores, carnivores... it's all in there. You can be your own underground, you can expand your underground by adding people to it in the fashion of affinity groups (people who collectively work together to achieve common goals, with lateral power). You could perhaps start an underground movement, but that won't last long before bursting out like spikes into the State. I like the sound of it!
Living on the underground is fun, thrilling, and rewarding. There's much more freedom. Obviously, I'm not underground, or in the words of the hipsters, "You probably wouldn't know what that is..." But I still know ;) It's an awesome band of freedom fighters, artists, and dissidents against the new world order that is formed every day in the hands of corporate globalization and consolidation of political authority in the hands of international psudo-governmental organizations such as the EU, WTO, NATO, etc. etc.
You have to judge for yourself how far you delve into this stuff. What's here can give you all the ideas you need to never be seen again, but will that make you happy? We are social animals, so you have to balance that somewhere. Only do what you must to protect yourself, and no more. It keeps everyone safe and yourself happy that way. Going overboard on security feeds fear and that breeds and spreads like a disease - how do you think we got to the point where people actually go on record to say thing like "I would like to have the police watching 24/7 so I feel safe"..... Don't forget to live, because taking away your own freedom is incredibly futile.
As to hackers....
The world is divided into White, Gray, and Black hat. White would be ethical hackers, the ones that operate legally and are employed. Gray ones flip back and forth between illegal and legal if the cause is right, but dedicate to neither side. Black hat hackers are the ones who are not phased by using illegal tactics for hacking, and hold no specific ethics. Anonymous is an collective of gray and black hat hackers - while some do very illegal things (which is awesome), some still operate with ethics (booooring). There is a small amount of people out there that are black hats and take advantage of fellow citizens. That's unfortunate. But it's a minority. The white hats are the ones to fear. They are the only ones who work for the government or private/corporate interests and can crash you down much more severely than anyone else could. $25,000 out of your bank account is nothing compared to life in prison. The black hats are the nice ones, it's the white hats that are heartless bastards. The black hats are the ones that are quickest to act against unruly government and corporations, it's the white hats that defend the bourgeois. The grey hats... they're just transitioning from being a pious prick to joining the fight.
So when it comes to hackers... don't trust any of them. But, if you wanted to anyways, trust the black hats. After all, if they really wanted to hack you, they already would have. The white hats will land you in jail. Think hard about it. It's a necessary mindfuck.
Perhaps one day I'll post something more descriptive - hope this works for you. Any questions, let me know in the comments.