You might get several different ideas from responses to your question, but what I have found most beneficial is if you know an upcoming turn is more than you can handle without moving your hands while making the turn, position your hands a little differently right before you turn into the turn.
For instance, if the upcoming turn is to the right, move your hands slightly counter-clockwise on the steering wheel.
If you are already into a turn before you realize how much of a turn it is, I have found it best to "shuffle" my hands. For instance, going into the above mentioned right turn, after the wheel is already turned, slide your left hand to the left, then slide your right hand to the left (rapidly, almost in one motion), and then do the reverse as the turn unwinds.
I don't normally recommend the hand over hand technique.
Steve Nix | 
Road Racing Sterrin Technique ?? 
