Liu Kang is annoyingly fast with his combos but easily defended if you see his pattern. I'd suggest going into practice with Kang and using his two combo starters (2,1,3) and (3,2,1) so you can get used to what they look like, that way when you see it online you will be able to know the best way to defend them. I'd also suggest trying to keep Kang out of close range by using (d+1), it will knock any over eager opponent backwards and make them think twice about rushing back in. From their it's all about using Kitana's awesome range to get those hits in, Her (F+2,1) starter is great for catching people of guard, another combo that always works for me is (F+3,1,Pretty Kick), it's short but people don't seem to block it.
I hope that makes sense, It's early in the morning here lol