I don't know how old you are but artificial nails did it for me. Biting or picking at your nails is a habit, and one that's impossible to break. I too have that habit, have had it since I was small, and nothing I've tried worked. So one day I broke down and bought some artificail nails and spent 3 hours putting them on (I've since got it down to two) and once I saw how pretty they were, I don't touch my nails. If they're long and pretty and look feminine, you won't have the desire to bite them. I've tried to go without them, and honestly, the very first day I'll find myself picking at my thumb, or scratching at a cuticle, and I won't even realize I'm doing it. So I put the nails on and then I have no desire to touch them, I just want to show them off because now they're 'pretty'. It's the only thing that has worked for me.