The sketch starts out very loose. I use a combination of brushes to build up texture all in gray scale. When I’ve worked the sketch to decent enough state, color is added on layers above the gray scale sketch. This workflow is similar to traditional water color and acrylic painters who use thin layers of color to build up their forms. To finish everything off, the sketch is flattened and color corrected. Highlights are worked in with the dodge tool. Color gradients are overlaid to tone the entire composition. That image gets flattened again and duplicated for the blur effect.