I'd be nice, just because I'm a nice girl.
I'd be overly friendly, and not flirty.
If he asked for my number (depending on whether or not he was creepy) I'd probably give it to him, and wait for him to actually make a 'move'. If he did, I'd shoot him down.
The thing is, is it's hard for me to sit there and turn a guy down before they've actually come onto me. So I don't usually lead them on, but I don't totally shut them out in fear of them actually only wanting to be friends.