Um... you probably should do a bit of reading, Mystery Method is a good place to start, some David DeAngelo stuff too.

While talking try to be fun and positive, don't talk about problems at school or work, because frankly no girl will really give a fuck.
Try to avoid boring stuff and boring-ass questions, like "do you like music?; whats your favorite movie?; Do u have hobbies" (u can ask them, but don't over use them) Its much better to state, rather than ask - "You look like a rocker chick."; "U must be a dancer."

Be fun - tell interesting stories about yourself, that demonstrate high value - "this one time I went out windsurfing and the wind stopped while I was in the middle of the lake, but luckily for me, these two girls were motorboatin' by, so they helped me out " (ok not the best story, but something that indirectly shows how awesome you are, but these hints must be subtle, but as Donston mentioned, don't make it seem as if you are trying to impress her!)

And I guess the last thing I might add, ... imply sexual interest. It doesn't mean that you should whip out your cock or anything, but say little things, that would hint that you don't want to be her friend, u want to be her lover. You can do that by being just a little "bold". (she offers to have a drink - you:"Are you trying to get me drunk, so you could seduce me?" ... "You just want me because of my body, don't you." (kinda keep implying that she is the one after you. but don't overuse it! )