I found intensive practice to be the best way to get accustomed to the tablet. Knowing all the keyboard commands for your application is also a must, since it allows you to just draw with your right hand.

When I worked with a mouse, my left hand was always poised over the keyboard to access all the tools/menus via shortcuts leaving my right hand free to draw. For anything that I needed to do often, I changed Photoshop's keyboard commands to suit my needs (I now have a shortcut key for rotate object 90º for instance).

Changing from a mouse to a tablet was a pretty natural transition. Since I work with a laptop I find I don't bother to use a mouse anymore; basic UI type stuff I can do with the touchpad.