I've been experimenting with a scribble style lately, with Star Wars as my subject matter. This experiment is forcing (sorry for the pun) to keep things fast & loose. It seems the more "successful" ones are where I push myself to just keep moving. Scribble more. Stop & adjust less. My line is a continuous line drawing (you don't pick the pen up from the page at all) using various black inks. Most of the color is watercolor paint, watercolor crayons or pencils. Some spots are non-diluted by water. Every so often I hit a spot with a dark blue china marker. And then I add some white gouache and black watercolor paint. This helps to keep things from breaking down completely, keeping to some highlight & shadow values. It helps give the subjects some form.
To be honest, the first one (Yoda) was the hardest. I wasn't feeling loose. I kept worrying about if things looked "right". It's hard to keep yourself moving. That perfectionist voice doesn't like that. So this is another way to beat him. Keep it fast & loose.
Today I did my Skywalker scribble. I chose this scene, rather than a straight up portrait, because this is my favorite scene from Star Wars: A New Hope. Luke's world has been rocked. His aunt & uncle are dead. He's at a crossroads. He must decide to stay behind and try to pick up the pieces or move ahead into an unknown (and potentially) dangerous adventure. This scene always speaks to me of hope, longing and a sense of destiny. Powerful themes in my own life.