Here's a post i made on Yahoo Answers a while back:
"Slowly get to know her, it may take up to 3 weeks to ask her to be your girlfriend.
Get close with her as a friend,
but don't stay in the Friend Zone
When it's time, let her know how you feel and etc;
Tell her how you felt from the beginning and make her feel good/loved/cared about
Be there for her when she needs you
and at times she doesn't, so she knows she cares"