Find a Common Interest
Find out what he likes to do, and see if you can find any common interests.
Maybe he has his own garage band and your big into indie bands, or maybe he is a sports fanatic and luckily so are you. Use the information to your advantage when striking up a conversation. When you are near him, talk to your friends about that great play that the quarterback made in the game last week, and make sure he can hear you. He may jump right into the conversation, impressed that a girl is that knowledgeable about the game. If you can't find any common interests, well, it probably is pointless to pursue that relationship.
Direct Eye Contact
When you speak to your crush, give him direct eye contact.
This lets him know that you are really interested in what he has to say. Smile, and if you're not shy, glance down at his lips once or twice. This will really give him a clue that you are not interested in just getting to know him as a friend.
Touch Him Playfully
Body language is everything when flirting.
When you are having a conversation with your crush, lean in to him as if you are really engaged in what he is saying. Touch his leg subtly or put your hand on his shoulder, or shove him slightly when laughing at something funny he said. This signals that you are interested and feel comfortable around him.
Get Caught Staring
If you see a cute guy across the room, stare at him until you catch his eye.
Hold the eye contact and give a small smile before looking away. You can do this a couple of times if you are not near each other at a party. The guy will be clued in that you are interested which will make him more confident to approach you.
Casually Suggest Hanging Out
If you are having a great conversation with a guy, but he hasn't asked you out yet, don't be afraid to ask him yourself.
Just be casual about it and don't make it sound like a date. If you have been talking about that new blockbuster action flick coming out, say something like, "We should totally go see it opening night. " Or if you are bragging about your bowling skills, suggest meeting up for a friendly competition. As long as you keep it casual, if he doesn't bite, you were merely having a friendly conversation and you didn't embarrass yourself with overt flirting.