Following some advice from Tom Preston, I decided to start gesture drawing, which is just a artsy-fartsy was of saying 'draw as fast as you can and don't worry about specifics too much - just get the overall flow.' Thirty second gesture drawing seems to be all the rage, but kind of hard to do and juggle photos, sketchpads, pencils, and an alarm clock.
Then I stumbled on the Figure and Gesture Drawing Tool, a nifty website with configurable tools to run you through a course of gesture drawing - as if you had a real-life old battle-axe of a art instructor in your own living room, yelling at you to draw faster. Okay, it doesn't yell, but it can certainly feel that way.
So, if you like to draw, and you want to get better, you might give the tool a try. I've been at it for a week or so and I may not be getting better, but at least I am getting more confident about my crappy drawing. One day I might even illustrate how poor Schmeky Encephalitis died in the Kobolds Ate My Baby game (for the second time,) or how my character Bloodspurt the Half-Orc Paladin in our Pathfinder game was ruthlessly executed by the party's assassin for being too annoying to live.
Until then, enjoy the hastily sketched NINJA!