1
Do your homework on the guy. You must ask around. Find out if he has a Myspace/Facebook/other social networking site. This is great for finding out what he's into, like music/films/general opinions. You can use this information to start up conversations later on.
2
Find out things he likes about girls physically. Remember, most men will fall for your looks before your personality. Not shallow, true. If you're not confident about your looks, start working on it. Get rid of spots, lose those extra pounds, whatever. If you know his history of ex-girlfriends, or girls he's previously dated in the past, or better yet his "type" (blonde hair, environmentalist, curvy build etc), then SLOWLY relate to that. The social networking sites can be helpful here.
3
Use mutual friends to your advantage here. If you see them talking, go over and join in. Your friend should introduce you, and voila! Now maintain the smiling and greetings every time you see him.
4
When you next speak to him properly, steer the conversation around to the internet or computers, and ask if he has Instant Messenger.
5
Go the extra mile. Stand out from the crowd. Do small things to get his attention, like if you already know him (albeit vaguely) make sure you are always there for him if he needs someone to talk to or if he needs to borrow something. Does he play sports? If so, you better get your butt on a bleacher with a towel, water bottle, and whatever else he needs. This way you're showing him you like him without telling him.
6
Let them feel manly! Seize control without them becoming aware by letting him comfort you through a hard time. Allow him to think he made you feel better.
7
Keep it real: be natural. Keep them laughing, smiling, and happy. Don't attention seek or complain about other people. Except maybe teachers/bosses.
8
Once you get a guy to like you, try to let go a little TINY bit so they can come. Ask your friends for their opinions if he likes you if you cannot tell. Maybe flirt a little with other guys. Play hard-to-get, but always be honest.
9
Don't change who you are! If you have to, he's definitely not worth it. Be honest, and don't be one of the girls that acts completely different around her boyfriend.