I had a tendency to bite my nails. Mostly because they would get longer than I prefer and bother me. It however is not a very sanitary habit and since quitting I've noticed that I don't get sick quite as often. That is not a problem for everyone but something to keep in mind. 

I started carrying a nail file around. Any time I caught myself biting my nails I would stop and switch to the nail file. Eventually you'll learn to use the file. And just so you know I'm a guy so the whole looking pretty kind of thing didn't play a factor.