A probably useful lesson for those bad at drawing rough sketches on a tablet

Using the water paint brush, draw and redraw the image on top of itself, making the brush smaller each time. (Use multiple layers, with the brush sizes going from 100px to 35px to 15px, for example.)

All that's left is to trace with a pen and paint in anime style, as usual. SAI's pen tracing tool is strangely easy to use. This time, I also outlined out shadows and highlights in pen, then tried to paint it artistically in an anime style.