2. Nail biting
Perhaps it was my worst habit, but thanks God I managed to kick it. My fingernails were always short and made my small hands look tiny.
One of the best tips to help with this habit is to paint your nails. If your nails have pretty polish on them you are less likely to bite them. If you do not use nail polish, then try to use special anti-bite and nail growth nail polish from the drugstore.