Since it is all mental, all's you have to do is WANT to quit. Make a conscious decision to quit. Even when you put your fingernail between your teeth.... STOP. Then rub your fingernail with your other hand. Also, it helps to carry an emory board to smooth out the rough spots.
1) I would suggest first developing ways to make your mind change from biting, idk like when you are thinking about biting nails then try to distract yourself with something very interesting 2)Get a nail polish that not clear and is very bright and very strong odor and apply multiple coats 3)Wear gloves; leather perhaps and not the ones where the fingers are open lol 4) Keep your fingers/hand busy games, try painting other friends finger nails for fun and don't wash off the paint that get stuck on your hands right away to remind that it is not to be bitten 5) Above all take time developing your method of stopping the biting don't go drastic 6) Set a goal and reward yourself when you reach it 7) Get other's to help if necessary
that's what i can say My brother used bite his nails all the time; all he stopped he still does from time to time
Simple.Think of all the things that you touch in the course of a day.Many people have been in contact w/ these items.Fecal matter,samonella,Ecoli and other bacteria are found on TV remotes,cell phones and anything that you touch all day long.Think @ it.