. While this might seem silly, pay special attention to not bite one nail of your choice. This will give you the discipline to start learning to quit this habit. You will start realizing that the more you bite your nails, the more you'll find it silly and nonetheless bothering.
Get some nail biting creams and oils. These typically are bitter tasting substances that you can put on your nails. They taste real bad, and you soon won't stand the taste any longer than you think you could. The point of these is to remind you that you shouldn't be biting in your nails so that you won't have issues with it.
Get some fake nails. These will protect your real nails so that you won't be able to bite on them as much. You may still find yourself with the compulsion to bite on the fake nails, but at least you aren't biting the real ones.
Keep something handy like gum or even carrots that you can chew on when you feel the urge to bite on something. This will be a substitute to use in place of your real nails.
Try tying something around one of your fingers or your wrist so that you can remind yourself through the day that you shouldn't be biting on your nails.
Try to deal with your anxiety. At times you bite your nails because you are nervous about something. Deal with this in a different manner than with nail biting. Learn to get rid of stress and deal with anxiety properly.