Most Helpful Girl
As a woman, I have taken the initiative to ask out guys I like. I went in blind a few times, with no hints. I just liked the guy and went for it.
I suppose eye contact, smiling would be like a subtle hint. You probably should show some interest at least if you want her to ask you out.
Most Helpful Guy
Alcohol. It will give you the confidence you need to ask her out and make the inevitable rejection a little less painful.