When you first see or meet him, you have to ask him to hang out quickly before his attention is lost, because there may be plenty of other options out there for him. Ask him out to a movie where the distraction will take away a bit of the first date awkwardness.
If it helps you feel more confident, tell yourself that if he likes you, it's probably just as nerve-racking for him to be talking to you. That could help you calm down.
Try to approach him in comfortable situations. If he's doing something that he likes, he'll probably be more confident. If he's in between classes or about to go home, wait until a better opportunity.
