Examples are: Nail Biting, Jaw Clenching, Hair Pulling
Habits develop as a replacement for stress, anxieties, worries, etc. Whereas at one point in time they served to relieve stress, as we get older they no longer do and are no longer needed. Thus addressing the cause (often anxiety or stress) and substituting healthier behaviors is the goal.
Many bad habits are very amenable to hypnosis, learn more about why in the video below: