I don't know if this will be helpful, but it's what worked for me. I picked my fingers for most of my life, to the point they would look bloodied and raw. When someone finally said something at work (and loudly) a couple of years ago was the day I stopped doing it as often because it was so humiliating to know that people noticed. Now, if I start to feel the urge to pick a lot, I think about how I want my hands to look and I even get occasional manicures now. They make my hands look nice and they also make it harder to pick, since the manicurist will cut off any dry or loose skin. There are times when I still pick when the urge is uncontrollable, but keeping my hands nice makes it a lot harder.

Like Lara said, keeping your hands busy is a good idea, too. It'll keep you occupied and burn off some of the fidgety energy that picking normally releases.