Completely ignore her for a few days, then send her a text message that just like "hey, whats up" or some such super casual thing. I found this worked well because the girl contacted me before I could get back to her. I didn't mean to ignore her, I was just dealing with life, but a little while later she was like "hey, you stopped talking to me, don't you like me."
Protip: you can't just say please to get the girl to cheat on her boyfriend with you (although you are pretty good friends with her and you guys play it off as a joke all the time even though she told you she wants to hook up more when she is in a relationship).
Addendum: When you try to break the girl and her shitty boyfriend up, she mentions how much she loves him and how he is the only thing that makes her happy despite how they argue everyday and the relationship seems to be based upon sex. When you say fuck it, and try to help her with their relationship, it leads to how she is thinking he might not be the one even though she loves him. This is the one who has sent you pictures of her in a bathing suit, underwear and just recently: schoolgirl outfit.
Third Strike, fight for the future: Girl is super involved in a youth group at church but has a crush on you, you have a crush on her. She can never go out alone (has to be with sisters, all older. They also can't go out alone) or on dates because of her wacky religious parents.
Fourth Dimension, 4-player super mario: Concert/House Party on Friday wherein friend in band promises that you'll meet a fly hunny, skeptical at best after previous attempts through him. See his ex girlfriend, the girlfriend after that's friend who was into somebody else already.
The above is pretty much the rundown on my relationship statuses with all girls I talk to. I am utterly confused.