Seriously, do just act like yourself. I'm sure that if he does like you back, he's probably nervous about whether you like him in return. They might not admit it, but guys worry about that stuff too, just in different ways than girls do. And if he doesn't like you back, then there's nothing you can really do. Don't specifically try to act in any way except what feels natural to you. Don't sexify yourself or pretend to be coy or anything like that. If that's the only way to get him, he's not worth it. But in the end, you will have to tell him that you like him, and not just as a last resort. Erm, I hope that didn't sound too harsh. You might, in the end, have to ask him out. Some jerk guys resent that, but most guys I know don't really have a problem with it. It lets them know that the girl is really interested in them. Especially if he knows you're the shy type- it will seriously impress him that you like him enough to risk letting him know you like him.