I watched a video of a drawing exercise in values and accuracy a while back.
Here's the idea: If you have an old pack of cards take one of them and rip it in two or more pieces. Lay it out and start drawing or painting.
I used an ace because of it's simplicity. Use any card from the deck (or use the image on the left). I almost chose the King but I didn't want to overwhelm myself.
This could open up many ideas . . .it did for me but they are yet to be painted.