I just generally get approached by girls I'm not into, then the girls I like tend not to like me back. Although if I want a girl I've found it's a numbers game. I've been known to (in my younger years) go after several girls from different bars/clubs/parties in one night until someone said yes. As a result I don't feel bad when I'm rejected. Yeah it's all probability, you never know what mood they are in at the time you approach them, if they consider you a catch, if they may be going through stuff in their life, there are so many variables, that it always is a numbers game at the end. Like my best friend says, take a chance, shit your pants.