Never take a girl who bites her lip seriously. Very quickly within meeting you, they will, either obviously or not, bite and massage their lower lip while staring right at you with eyes wide open. Lip biters are usually very pretty girls who get a kick out of their power over men; their goal is to arouse you to action where they can then frustrate you. The fun for them lies in the frustration, not the arousal.
Dealing with these types of girls are easy enough: simply remain unaffected and let them wonder why their usual game isn’t working. Then they try even harder. In the process they will devote more and more time and attention into you, and next thing they know, they are into you and can’t quite explain why. But even then, it takes forever to get these girls in bed because of the hoops they make you jump through. If you do get the lay — and odds are you won’t — it’s definitely not worth your time to stick with them afterwards. You will never “win” with them and never crack through their game-playing exterior to find the real girl inside (if there even is one). Whether they are playing unconsciously or not, let some other chump try to figure them out.
Either you will get played hard or will not get what you want, which I hope is a normal girl who cares about your needs. I did not meet my first lip-biter until I was 22 years old. She gave me incredible pleasure, but in the end she destroyed me.