I agree with what Stein and Barney are saying but don't be too worried. As your confidence raises with the approaches and you relax more you'll become more aware you are the one controlling the interaction. If you can't think of anything to say you can say to her "Your so cute and now I can't think of anything to say haha". If she laughs too, bingo. The absolute worst thing you can do is think to yourself "shit I'm running out of things to say". If you think it your fucked basically. So don't think just speak.