This is hard because if your crush doesn't like you...it's setting you up for trouble. But if you wait for the crush to pass while keeping quiet...your crush might like you and you'll never know it! You don't just casually say, "I have a crush on you," either, so this is really hard, but I'll do my best!
Does your crush often talk to you?
Does he/she smile at you?
Does he/she blush when you are around each other?
Is your crush shy around you?
If "yes" is to most of them, he might like you! Even if it's a "no" to all of them, he still might like you and just have different ways of showing it! Either way, the best thing is to tell him-or honestly, it may end up being the worst!
It's a tricky thing, but you have to take chances.