Gosh, this topic is old! But it's still open, so I think I'll post again, with more up-to-date advice from a more up-to-date and more mature me.
So anyway, telling a guy that you like him IS a pretty scary deal. I don't mean scary as in horror movie scary, or "OH MY GOSH!" scary, but just nervous and, well, scared scary. I think that you should just hang out with this guy, and flirt a little. Don't go overboard though, like "You are just so cute!" or start acting really weird. Smile, flip your hair around a little, compliment him, and just be yourself. This is enough to let him know that you like him, but if you REALLY have to put it into direct words, wait for a little. Watch for signals that he likes you or not. Does his face light up when he sees you? Does he laugh and flatter you? If not, he might just want to be friends or is just really secretive with his feelings. If signs point to that he DOES like you, go ahead. Find a quiet place to talk to him, and show him your feelings. If you're careful, and if it's meant to be, you have nothing to lose.
Oh, and if this is a boy that you don't really know, say hi and start up conversations. This will give you a chance to really get to know him (and for him to get to know you) without screaming at the top of your lungs "I LIKE YOU!" That will just scare him away, especially if he's someone that you've just met.