Go for a professional manicure once every 2 or 3 weeks, suggests Angelica Kaner,PhD, a clinical professor at Yale University Medical School, because when your nails look pretty, you'll be less likely to snack on them. At the very least, keep your nails trimmed short. You'll have less nail to bite, and that harmful bacteria has less space to grow. Nail biting is also a nervous habit that is often an expression of some deeper anxiety. Ask yourself why you're feeling anxious,kaner say. You can also try subs toting a new, healthy behavior instead of biting your nails, rub in a cuticle cream or oil