Think I won't play as many online games..
found your problem right there. When it comes to fighting games, playing 'local' is always a good place to train. Get some friends (pref who are equally on your level or better) and practice with them. I can't quite explain it myself, but it is different, because you can talk to your opponent directly and get input/feedback/insight on your level of play.
if you keep on "choking" on matches, then simply relax... I'd say don't aim on trying to land combos, and just focus on doing damage... if you mess up a string/combo starter, DO NOT attempt it again and again in a match, it will just throw you off, and you will become readable like an open book. If you're trying to close a match, don't hurry, the timer is your friend. If it is a very close round, and both of you are just 1 tick away from a KO, dont get stressed

in a fairly balanced game like SF (4 or otherwise), there's no such thing as a 'cheap', there's are effective and not-so effective... don't feel bad about spamming tigers or srks, its your opp's problem if they can't handle them. case in point, "Flowchart Ken", people sure love to complain about it a while back, but it has died down, because they learned the game, and they've gotten around it, and stopped losing to it.
So when you see an akuma online, showering you hadous, dont get frustrated, its not his fault that that's the only way he knows how to play the game. But it is your fault for not trying to figure out an exploit

(hint: akuma has shit health)
don't lose hope.. go to training mode... learn every normal, look at distance and range, take note of the difference between a short tatsu and a roundhouse tatsu, etc... even better, know the record input function of the training mode? use that, like, have ken do 10 srk's in a row, and try out which 'counter's work best on every situation (distance, jump, etc..)
but my best advice is to just have fun. we may never be the next top 8's in Evo/SBO/etc, but at least enjoy trying to.
then again, what do i know

i've been playing SF/Fighting games non-stop since i was in gradeschool, and i still suck