the first thing to do: talk to someone during class. classes are boring and good for slipping in a hi or two. its really easy, ecspecially if youre like me and tend to make comments during class. its not necessary though. see a guy who seems cool? look for something to say. he could be wearing a shirt with new york on it, ask him if he's from there. he mentions to the teacher he didnt have his homework cause its in his car that broke down? ask him about it. or just mention that this class blows or if he needs help on the problems.
body language is a big key. dont be a hunched up, nerdy style. stretch your legs out comfortably, lean back in your chair, keep your chin up, give a smile when people make jokes. you dont have to be joe jockman confidence yet, just dont be closed off and antisocial looking
ask for a name. 'whats your name?' 'jake' (nod) 'im danno'.
now when you see these people at lunch, walk up and say yo man and say what comes to mind from the earlier conversation...man even i'm gonna have to get help for those goddamn pages she gave us for tonight...just light conversation. its not hard, watch seinfeld and you'll eventually be able to get conversation out of anything. literally.
girls is probably more important, but i would work on social proof first just to get a feel for things. you can work on girls anytime, anyways.