But about your pick hand, tendonitis isn't that common in your picking hand, that usually happens to your left hand. But carpal tunnel is more common by your thumb from overuse (basically, galloping, alternate picking, playing rhythm, etc. every day).
Do you usually play every day? If so I would take a couple days off. Also don't overlook ice dunking. I do that every once or twice a week to prevent tendonitis.
But anyway, I tend to hold my pick like this: http://guitarless.net46.net/holding_pick.html
