Err...how can she see you as a good friend if you have never done anything together?
She obviously likes you - otherwise she wouldn't say yes.
Accepting date doesn't mean she wants you to be her boyfriend...nor does it mean she doesn't. It's simply best to go on the date, show interest (not needy interest), make jokes, compliment her just the once on something that is unusual but likeable about her (or that she's wearing), give her a little bit of space occasionally to let her move towards you (creating a vacuum occasionally - so to speak, for her to fill)....and see what signals she gives off before deciding where things will go from there.
A note on compliments - they should always come across as genuine. Genuine compliments do not need her to become flighty / greatful / starry eyed etc. They just are, and are said because you think so - not because you seek any reward. IF she is insecure (a large percentage of young women are), it's best to make the compliment, followed by you immediately commenting on something unrelated (ie it doesn't give her reason to object to the compliment, which then creates awkwardness)