Also, if those hands are fleshy, like severed limbs: paint them a dead flesh color. Not nice and pink, but several shades lighter, and yellower. Think like almost chicken skin. Then take a sponge with bruise purples, and reds and b even black and brown in successive passes and lightly stipple discoloration around the cut off edges. Don't forget to discolor the fingernails too!
I found this hand on Deviantart. It's a pretty good example.