But characters have right hands too! Since I can't draw with my left hand to free up my right hand for reference, I just flip the DIGITAL drawing horizontally so that the characters right hand is now his or her left. Now I can draw it and just flip it back later.
So when you see a right hand drawn from me...it's really a left hand...I just draw left hands.
Flipping the image also helps you see wrong proportions, tangents, basically stuff that is "OFF" so it's good to flip the image back and forth when you are working on it.
But what about traditional hand studies? Once I figure that out, I'll write something, but for the time being, maybe mirrors or those nifty hand mannequins.
Hope someone finds this useful.