Laugh a lot. This always gets a guy's attention. Just don't be crazy about it, laughing every ten seconds at anything he says could make you seem unreal. Also, smile a lot , not so much it's cheesy, but show him you are confident with yourself.
Find out what he likes doing and be there doing the same thing. Do you both like sports, or maybe science? If you can, be in the same place with him doing the same activity.