how do i stop skin picking?

hi, i stumbled across this site as a was searching for a book or c.d to help with my skin picking. i have been picking at my hands for more than 20 years and i just turned 30. its not the little hang nail but i pick the sides and pads of my fingers until they are raw and bleed. i'm always hiding them. i'm about to graduate nursing school and my boyfriend is worried that i'm at a higher risk of infection, i know he's right. A couple weeks ago i was at the hospital and my fingers were so red and torn from my recent picking that everyday tasks were painful. This habit seems above me and i don't know how to break it. Does anyone have advice or can someone tell me how they have stopped? heather