Can a Liu mainer help me? I want to pick him up, but I don't know much about him aside from basic bnbs. So, how can I keep pressure on? Does he have blockstrings like Cage? Best usage for parry? And of course, how to play him in general?
Only strings you really need to know are b312 and f12. b312 is your best low combo starter and highest damaging launching string; I believe it's also the launching string with the fastest startup on the first hit (12b1 might be faster, need to look into it) so it's also what you should use for punishes. When b312 is blocked you can do another b312 right away and this can only be interrupted by a move 8 frames or faster. Depending on what your opponent is using to interrupt your blocked b312 strings, you can follow with cross over jump, d3, f12, or dragon stance; the most important thing is to make sure you keep them guessing so that they're scared to try and interrupt.
f12 is what you use to get in. It's two quick advancing jabs that move you roughly dash distance forward. It's safe on block and after it gets blocked you can go into b312 pressure. The reason to use it in your block strings is because if your opponent tries to jump backwards it will catch them out of the air and send them into a juggle state, getting you a full combo.
Because of b312 people are going to want to block low all the time, so use f3 as an overhead. You can't combo after this but it puts you at high frame advantage allowing you to keep the pressure on. Don't ever use f3 after another string is blocked, because if your opponent is trying to down poke their way out of your pressure it'll just stuff the f3. Try to use it off a jump or when you're at frame advantage.
213 is a string you can use as an overhead option (the last hit overheads), but it's kind of a gimmick and I don't recommend it.
Liu Kang's zoning game is really strong. You can alternate instant air fireballs with low fireballs to make it hard for your opponent to advance. Instant air fireball spam is also a good way to build meter.
Your kick specials are not that good. There's some situational uses for flying kick but when you're just starting out I would advise you to not use it ever. Bicycle kick is good to end combos but again not very useful. XBlades loves to enhance the bicycle kicks for the armor, I respectfully disagree with that strategy.
Parry is not as useful as it may first appear because you can get hit out of the startup frames on it. It's good for wake up, for anti air, and to bait out your opponent's advancing special moves (Nightwolf shoulders, Johnny Cage green/red kicks, etc), especially on wake up.
Also Liu Kang has the best X-ray in the whole game (imho) and as soon as you get three bars you should just start mashing it out with reckless abandon for the consequences. Try not to do it from too close though; even though it overheads, they can duck it if you're too close and it will just go over their heads.
I think that about covers it.