For some nail biters, it's about obsessively "fixing" problems with their nails. One solution is to keep your nails groomed. Manicure kits usually contain tools such as nail clippers, a file, small scissors and a cuticle pusher or orange stick. If you keep a kit with you, or even just carry a file, you can take care of broken nails or hangnails without biting them off.
Try giving yourself a manicure once a week. Start by clipping your nails if necessary, and then smooth the edges with the file working in one direction. Soak your nails for a few minutes in a bowl of warm water with olive oil or lotion added, and then gently push the cuticles back with a pusher or stick wrapped in cotton. Dry your hands and finish by rubbing on more lotion or a cuticle cream. You can use a buffer to make your nails shine.
If you can afford to get a professional manicure at least a few times a month (and they're for both men and women), spending the money may function as a deterrent. Polishing your nails with colored or clear polish can also help because you won't want to ruin your work. And don't just stop at polish – these days there is a dazzling array of nail décor to choose from, including, jewels, patterns, and textures.
If you've tried the manicure and it's not working, don't worry. There's another deterrent that involves doing something to your nails up next.