okay first of all, you have to THINK you're hot shit. remember in the 40 yr old virgin when Andy acts like he's the bomb and ends up attracting the hot girl in the book store? at first he couldn't think he could do it, but he acted the confident part and she wanted to jump him. a little bit of over confidence is good, too much makes you look like a jerk. but most guys can find that happy medium.
signals can be difficult. first off we love a chase, so we may give you the green light then run away. we do it all for a reaction. next time you think you're getting a signal, say something coy. innuendos always go a long way. and if she is thinking on the same page as you, she'll pick it up instantly (unless she's clueless and dumb in which case move on cuz you don't want to waste your time on those kinda girls). if she plays too many games, move on, cuz she's obviously trying to be a playerette or something. just go with you gut instinct.
chances are she's prob a little nervous too, waiting to see if you'll make a move.