First, if you have trouble drawing hands and feet, draw nothing
but hands and feet until you get them right. Use your left hand (or right hand if you're left-handed) for reference, and using a pen, just draw your hand poses. Same goes with your feet. Take pictures if you need them at different angles, or draw your friends/family's hands and feet.
Photographs of hands if you need them.As for a good program, there's Gimp and openCanvas 1.1 out there (both legally free), just Google it. Paint Tool Sai is also pretty popular, but it's about $50. Just remember that a program is still a tool, just like a pencil, it won't do anything magical to your art if you don't know how to use it.