As any cigarette smoker knows, habits can be very hard to break. Nail biting is no exception. And while we don't advocate substituting nail nibbling for something as dangerous as smoking, there are several less lethal habits that can help a biter reign in the habit. Some examples of distractions that can be very powerful deterrents to biting include humming, finger tapping, gum chewing, or candy eating.
The downside of adopting a new habit to kick an old one is that, even if it works (and it may not), you might find yourself stuck with another equally troublesome tendency. This usually isn't a problem for the singing set, but it can be disastrous for candy eaters. Nail biters have enough to worry about without the added stress of rotting teeth and weight gain.
If you can't find a suitable distraction or habit to help you stop biting your nails, you might try addressing the problem therapeutically. This can be tricky since nail biting is not generally considered a specific disorder and most remedies are of the do-it-yourself variety. Still, there are other options for the would-be quitter, including online support groups. You could also find a "quit buddy" to help you on your journey to a bite-free existence.