Q-unit nailed it. It is all about sending mixed messages:
You SHOW her you might like her with your actions
But you don't ever tell her directly.... your words should keep her wondering
It is like with coc-ky funny: you always talk to her like you are the motherfuggin boss, with a lot of humor thrown in so you aren't just a jerk.... but with your actions you show her you're really a good guy.
If a girl asks me if I like her I would say: "not particularly, but there's always time for me to change my mind"
or you might dodge the question for fun and say: "yeah, you're a good friend" and drop the friend-bomb on her ass...powerful
or: "no, I only like nice girls"
or: "does it matter?" "you like me one way or the other anyway"
don't actually tell her you like her, that is almost never a good idea.... takes away challenge, mystery, anticipation, and many other things that cause her to be attracted to you.