what I found to work for me, and really well (I have been a nail biter from childhood) is to just spend money on your nails... always keep them looking pretty, and you will stop (b/c they look so nice with no raggety cuticles and a nice lacquer on them!!)
I first would recommend getting a professional manicure, or if cost is an issue, just invest in the care of your nails... pick up some nice cuticle oil and nail growth polish (well, likely you'll want a nice glass file to clean up those chewed edges!!). Then keep your nails always with polish on, and that tastes bad (then looks bad if you bite them--no one likes chipped polish!) so you'll stop eventually. Trust me!! I am in law school--and used to be a stress nail biter.. since I started taking care of them, I no longer mindlessly chew on them!!
I totally recommend butterLondon's Handbag Holiday cuticle oil (smells fab--tropical and works great too) and Horsepower Nail fertilizer... your nails will grow fast and strong with these. Also, for a less expensive option, look into Sally Hansen stuff at any drugstore. But butter nail lacquers are AWESOME!! I am nearly as addicted (nearly, but not quite LOL) to that company as I am MAC....
What is butter london? : butter LONDON : Long Live Nails
HTH a bit!! Good luck... and welcome to the forum!