I am starting a week of daily hand drawing, here's todays page :
As a general base for my studies I used Bridgman's more sculptural approach. Don't worry about individual muscles on fingers or how everything works underneath, but instead focus on the general broader shape. You can get the free e-book here: http://www.scribd.com/doc/4461737/Constructive-Anatomy-by-George-Bridgman
I used posemaniacs for the references, they provide free 3d models that you can rotate in full 360 degrees. They are not detailed so it's easier to be general with your description of the hands. When you pick images you can easily get stuck on value, color, wrinkles, etc.. These force you to stay simple!