I'd start with her hair. Ask her how she makes her particular style work, but don't dwell on it for too long.
Other fairly good questions to ask include "Have you seen any good films/movies recently?" and "Have you heard any good music/songs recently?"
Of these 2 questions, it is only good to ask one rather than both - otherwise she'll know you're trying to find out her preferred genres.
As for knowing which question to ask - if she says things like "That sounds like a good idea." rather than "That looks like fun.", then she'll probably be more into music than movies. If not, then she's probably more into movies.
The fastest way to mess up this approach is to ask "What sort of music/movies do you like?". While this seems like a thoughtful and selfless question, some girls consider it to reveal that you know very little about them.
Subtlety is the key - get her to talk about herself. That way you'll know if you'll enjoy doing the same sorts of things together. And when the subject of conversation changes to yourself, don't boast, but also don't be too modest. Find a balance.
One final thing - after your conversation together, do some research about the things she likes. That way, you'll have more to talk about next time.
If I'd known this 15 years ago, I think I'd have been surrounded by ladies at the time.
