First off, you must learn to block. I would almost suggest it before learning any special moves, but I know how many of you eager people are and that is your least concern. You want to learn special moves. But I'm telling you now, you can know every special move in the world and if you don't know how to block they will not help you one bit. Blocking is in essence the essential to living. If you can block, you can live. Otherwise, people are going to have a field day showing off on you at your expense. Practice a lot and get very good at it, and soon you can defeat people with just regular moves.
Lesson 1: Blocking high and low. The most important part about blocking is knowing when to stand up or duck to block. When you block, you must always hold the controller direction away to where you are facing, or to whatever direction you are to your opponent. If you are on the left side, hold left to block, and vice versa. Whenever your opponent is in the air, always stand up to receive the attack. I promise you every time that you are blocking low and someone is doing a jump kick your opponent will hit you. You must stand up for these sorts of assaults. Otherwise, and ANY OTHER TIME, block low. If your opponent is standing up on the ground, block low anyway. They can always sweep kick you until you start blocking low. Some people will just sit there and continuously sweep kick you until you are dead until you figure out how to block. So the sooner you learn to block it, the better. Block high when they're high (in the air), block low when they're grounded (on the ground).
Lesson 2: Blocking "high" non-air attacks. The only exception to the blocking low rule is when characters use a "medium" normal punch or kick. These are usually noticable, and they take time to execute. For example, Ryu and Ken have a medium standing punch (kick for Ken) that when they walk toward you, they raise their fist (foot) high in the air and then begin to swipe it downward. You'll know what these are soon when they start hitting you when you're ducking. They also usually hit for a 2 hit combo, and don't really do a lot of damage, but it is enough to throw you off. The disadvantage to them (surprisingly...) however is that it has major lag time. With practice you will get good enough to recognize these sort of attacks, and will have plenty of time to either jab them quickly before they hit you, or you can stand up fast enough, block the move, and then do a small combo or special move of some sort. You have the upper hand at that point, so take advantage of it. Eventually your advesary will get the hint that you are good enough to block that sort of nonsense, and will more than likely avoid using it from then on.
Lesson 3: Throwing and Blocking don't mix. A hard and tedious lesson to learn. Throwing cannot be blocked. Period. Someone can come up to you, pick you up and hurl you through the air, regardless of how long you've been blocking. When you get good enough at blocking, usually opponents will try to pull these stunts on you. Don't let it happen. Get good enough to counter this sort of action. There are usually two common signs on when someone is going to throw you. The first is when they are jumping in the air and they do "unusual" things, or they are on the ground moving toward you, and not attacking. The air problem is usually harder to notice than the ground problem, because you will expect them to do things (and then they don't) and you will get confused until it's too late. Usually fighters have a pattern to their attack. They'll jump towards, hit kick or punch to try to hit you, then jump back (as an example). When you notice that they attack "too soon", they are lagging in the air. At this point they are vulnerable, but you may take interest in your brain, "Wow, that was kind of stupid" and as soon as they land, they throw you. This is because by the time the lag is over, they are able to throw you, and opponents will do this just to confuse you. If you can catch this and can react fast enough, hit them during their vulnerable time period to keep them away from you. Some other opponents are also on the defensive, and will be anticipating this. So they will not attack AT ALL. They will just jump in the air and wait until they land to throw you. If you do attack, they can block in the air (SFA, SFA2, SF vs. X-men), or they will just chance it. This is much harder to deal with. If you do perform a move of some sort, it can usually be countered by the block, then while you're recovering, they can walk up to you and throw you anyway. Or if you just sit there, naturally they can throw you. So how do you deal with this? Wait until they land, then throw them back! This is so hard to master at times, and if you are dealing with SFA/2/X-Men, and they do happen to throw you it will generally end up in a "Tech-Hit", taking off minimal damage from you if you happen not to throw them (the same goes for them if you throw them.) If you get too scared from this idea, standing jabs (remember, if they're in the air, stand up!) will usually push them away at least, and the lag time will be too low for them to be able to throw you. Or you could always jump backwards and punch/kick to avoid it, and hope not to get stuck in a corner. These two are not the best counter moves, but it could be the safest for you. It is much better however to turn the tables on your opponent than to just play it safe at times. Keep practicing, and you may just find that throwing them back is better after all. And if they are running up to you on the ground, just pummel them. Do a special move, sweep kick, jabs, but keep them at bay. They'll get the hint and try something else, or make a mistake. Just make sure you don't get distracted.
Lesson 4: Blocking Special Moves. Yes, these little buggers are game changers. One who masters blocking will know how and when to block these special moves. The trick of this is actually quite simple. Don't block unless you have to. Since even blocking these special moves will still do damage, avoiding them at all costs will save you life, even if it is a miniscule amount. After blocking five or six of these, you might as well have taken one full hit. And if you get a special move happy go lucky person on your case, they may just do that to you to death. (I happen to do this quite a bit). Jump over fireballs and counter-attack, slide under them if your character has this option, teleport, back off, whatever it takes, but try to avoid it. Yes, there are times where you are going to need to block these (better to block than to take full hits!). Plenty of them. But avoid as many as you are able to. That extra life may just be your life saver. :) This takes time to learn, especially since every character has different ones that you have to handle. See specific characters and their traits and imagine how to deal with them. When I find time to actually do this as well, I will post up how to defend and use these people (and special abilities) in the future.
Lesson 5: Blocking "Super" combos. The same general strategy goes for these too. Avoid them if you can, but more than likely you'll have a tendancy to block these more often. You don't want to take chances with these things. These will make you lose the game if you get hit by one of these and you're not prepared for it. After you see the amount of energy they take up when you do get hit by one of these you usually have a tendancy to just give up. Even when blocked they take quite a bit of life away, but they are quite vulnerable after executing them. ALWAYS use this to your advantage. If you have to take some, you might as well give some back! Another good way to counter these is to actually hit them. I know it sounds stupid, but if you time it right before they actually deliver the super, they might end up just wasting their chi power. It takes a lot of practice though, and sometimes you can even do it in mid super (maybe a fireball perhaps?) If you do happen to take a major hit, don't give up. You can always make a comeback, regardless of how impossible the odds you think they are. I came back from an opponent with a full amount of life when I had none left, not even enough to block. They just got too cocky and expected that "one last hit..." Well, that one last hit lost that person the game. I got to give it too. ;)
Lesson 6: Air blocking. This lesson I'm a little too unsure of. First of all, it only applies to SFA, SFA2, and SF vs. X-Men. The older versions don't enable that at all, and SFIII doesn't either. Personally, I didn't like it at first because I was so used to not being able to block. Now I kinda like it because it makes the game more challenging and interesting. Then SFIII came out and messed me up again. I don't know if this phase will last, but I really wish that Capcom will make up their mind. Anyway, if you are playing one of those versions (my basis will come almost exclusively from SFA2), remember that even special moves (and for the most part, even supers) can be blocked in the air, and that's a really nice thing. This includes the dragon punch, a formerly unblockable move in the entire series. This comes in really handy when you are jumping away from an opponent (or towards one) when you really need to get out of (or into to cause) some major trouble. Just remember, just before you jump, you won't be able to block. You have to actually be in the air for a miniscule of a second to block. This comes in handy when you're trying to avoid special moves and you end up blocking one anyway. Hey, you tried. It's nice to have some insurance though just in case.
Lesson 7: Be ready when getting up. Time and time again, opponents of mine forget to block when they are knocked down. Just as you are getting up, be prepared (and even in) a blocking position. I don't know how many times I've sent fireballs in their direction as they were getting up and they just took the hit. You can block it. So do it. Don't just stand there like an idiot and take it. The same goes for any other kinds of moves. If someone sweeps you, hold down and away so they don't sweep you again, and hold this position even if your character hasn't even flipped up yet. Your character will notice this, and before your opponent hits you, you will end up blocking it anyway. Of course, if they are in the air, then stand up and be in a blocking position. This is how many opponents will take advantage of your non-blocking or bad-blocking skills and perform combos beyond oblivion on you. But knowing this may save you, and may even be their own downfall. Try it on them and see. They may just have that flaw in blocking after all, so use it against them.
Next General Lesson: Getting those special moves to work all of the time, and playing with your opponent's mind for weaknesses to use against them. Have fun, and hope these tips help you.