Danman1 knows his shit.
If there are MANY moments of silence which then become awkward, purely cos neither of you have anything to say, then bail. It means you just don't click.
But if you want to just shag her then START FLIRTING!!
Seriously, flirt your ass off.
IF you want to hook up with her you just act interested in whatever she's saying and make jokes. I don't mean knock knock jokes, but perceptive jokes, like crack a comment about whatever it is she's rambling on about.
MAKE EYE CONTACT AND SMILE (not creepy stare & grin - that's fucking lame).
PUT UP WITH HER BORING CHAT - pretend you give a shit, and make a few sex jokes - shows her you have a cheeky side, which i'm guessing she's never seen before. Piece of piss and gets her thinking about sex.
DO NOT BE FAT - it makes things tricky and you don't want more unnecessary obstacles for yourself.
FLIRT.
ONE MORE THING - Dude, you already know she's a bit of a whore, right?....so......WIN!
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EDIT: I just read you're both 17....man, you're young, don't feel bad about this. It's alright if you shy away from opening up to a girl, but try this - pretend you're someone else, honestly, just act totally different from what she's known you to be, but do make some cheeky sex comments, all girls love this but practice infront of a mirror first.
A MIRROR IS YOUR FRIEND!