I’m blocking someone trying to hit me? Every time i try to go out of the block and counter, I start getting hit with all kinds of combos. How can i counter someone after blocking without getting hit as soon as i come out of the block?
Block more. Seriously.
Eventually the person attacking you will be pushed far enough away from you that you can move. The person attacking you WANTS you to mash them buttons and end up getting hit some more. JUST BLOCK. Mashing jab will not help you. Unless you play Balrog.
If you’re getting so mixed up that you don’t know what’s going on, observe their attack patterns and see if you have something that will counter it clean; SRK, good backdash, etc, and do so at the appropriate time. If you don’t, BLOCK until you can get out.
Just because you’re not blocking anymore doesn’t mean that you should be hitting buttons. That’s how counter hits happen.
You know the only way someone can hit you in this game if you’re blocking is to throw you, do an overhead, or do a crossup/fake crossup? And you can react to those pretty well.
Read up on “block strings.” This is kinda what G-Boobie is talking about. My (admittedly limited) understanding of them is that there are certain characters who can execute a chain of normal moves without you being able to respond. The reason you can’t respond is that they recover from executing the move faster than you recover from blocking it.
So while you’re character is still reeling from the block, they have already begun punching/kicking again. And once the block string has finished, they can execute a move or combo designed to capitalize on you trying to respond.
I main Chun Li, and one way I can occasionally interrupt athis is with an EX spinning bird kick. I think most characters have a similar move, and some (like a dragon/tiger punch) are better than others. I’d recommend visiting the character specific thread for your main character and asking what moves they use to interrupt block strings.
Number 1 Rule = The shorter the blockstring, the better. Also learn spacing, stay out of the zone where characters can start to do moves on you. I’m not quite sure who you main but also figure out some decent Anti-Airs to stop them jumping at you. Also, it’s good to block sometimes, you don’t have to try and hit them all the time. Chances are when you’re blocking, they’ll do something stupid, an unsafe move or something and that is when you get them. Hit them with your most damaging combo and knock a sense of fear into them, that way they’ll be a bit more weary when approaching you, and you have the upper hand mentally. Once you get a knock down and your using an offensive character, don’t let them move…literally. Just keep pounding them over and over again with what you’ve got, however, if they start hitting you…BLOCK. Some people seem to have the mentality that’s it all about offense, offense, offense but sometimes blocking can really help. But all this comes with experience, play some good players and soon it’ll all just come naturally to you 
Also, what game are you playing?
you’re going to have to learn about block strings.