What should I do to be more than friends with her?

I met her a while ago but hung out with her a month ago and one other time since then. she is my friends girlfriends friend. the last two times we have hung out, we have talked and joked around alot. we talk alot on face book chat and she almost always ims me first, and we talked once on the phone when she was with my friends girlfriends friend who im also friends with. Sometimes she asks me about one of my friends she hooked up with that she hates now. The problem is that I have called her my friend before and she has called me her friend. At first I did just want to be friends but the girl i was going for didnt work out, so now i want to go for her mostly cus shes just so easy to talk to. What should i do to get her to be more than friends?