Actually, a movie is a bad choice for a first date, cause you don't really talk, but watch the movie.
Anyway, if you're out with her, check our for signs, like Darth said:
Does she touch her hair when you're around her?
Does she touch her shirt, or scrach a lot?
Can she keep eye contact with you?
etc etc
Bet with Dr.A.Peter.Nintendo that Super Mario Galaxy 2 won't sell 15 million copies up to six months after it's release, the winner will get Avatar control for a week and signature control for a month.