I'm a fellow nail and skin biter and have also found it to be a very horrible and embarrassing habit. I would just love to quit but have realized over time that there is absolutely no straight-forward cure. I have been battling this my whole life.... ie from 5 up until now and I'm about to turn 20. I have done as much as i can to stop, i have bought gloves, used moisturizing creams, used those disgusting tasting liquids, used false nails, painted my nails and asked my mother and father to continuously remind me when i'm doing it so that i can consciously stop. However NOTHING as of yet has worked for me. My next step is looking to be hypnosis although that is too expensive right now.
My reasons for biting my skin and nails i believe is because i am constantly anxious and over think things in my head which cause me to be stressed out. My main problem at the moment is with this habit and it is most probably due to the fact that i have some kind of obsessive disorder where i see putting my hands to my mouth as a means of comfort and self soothing and to be honest that is exactly the type of relief that i get when i do it.
I have discovered that when i keep my self really busy by continuously going out as much as possible and not thinking about things which make you really anxious then this can help. Personally a lot of bad things have happened in my past and every time I am bored and daydream ie while watching tele or driving or in class etc i will bite and bite until my feelings are once again suppressed. The fingers which i mainly bite are my thumbs. I personally going to find a solution and then come back on here and let you all know.
If anyone tells me that i clearly dont want to stop biting my nails thats why i havent already.... then dont have a clue what they are talking about because i really DO that was the purpose of trying every possible method given to me.