I know they always say it but, just try to be yourself. One thing I've learned about conversation is that the conversation has to be two sided, that means that both parties have to be interested in what is being said. The best conversationalists I know are good at changing the subject until they land on one both people are interested in. Try to listen to her when she talks and THINK about what she says. Don't feel like you have to respond a certain way to please her. Pick out clues in what she says follow the clues, ask her to expand on certain things. Don't try to act like you know about something that you know nothing about, she will respect you more if you are honest, maybe ask her to explain more about a certain subject... for example if she says she likes to ride horses and you know nothing about it tell her as much, ask her what her favorite thing about riding is... if it sounds like something you might want to experience, use this to your advantage, plan a date around her teaching you how to ride and then suprise her. Use conversation to learn about each other, to get ideas about dates and romantic things to do, to comfort each other when you've had a bad day. Don't talk just for the sake of talking because that will get you nowhere.

Hope this helps,
Tennyson