This is the result of experimenting with the airbrush tool, which I have hardly ever used before. No textures, references, filters, or anything of the like - just the airbrush tool in GIMP, with occasional use of the eraser or accidental use of the paintbrush (which I always switched back to airbrush the moment I noticed).

'Course, as soon as I finished and uploaded it, I started seeing a million things wrong with it. But it still represents progress.