Just be yourself, don't try to impress her, just be what you are with your close friends. If she likes you chances are it is because of what she saw of who you ALREADY are and not who you might become, so just be open but nice and go for it. In Budokan Ninjutsu there is a saying that "when you do it, do it without hesitation" i.e. no second thoughts, just action. If she is right for you she will respond with equal measure. If she doesn't, move on, sooner or later someone will and then you'll know she's the one.
You live only once so might as well enjoy it.