Biggest mistake you could ever make is to "ask out" someone you aren't already friends with. A relationship doesn't just happen, it develops. If you know each other pretty well, just go for it. Ask her if she wants to catch a movie sometime, not "do you want to go out with me" because that's loving lame and makes you look like a pusillanimous individual. The important thing is that you need to be comfortable with being around her and she needs to be comfortable with you. If this isn't possible, if you just don't "click", then you're wasting your time. Move on to other possibilities.
tl;dr stick it in her pooper
Poll