Here are a few drawing phases (roughly skipped I'm afraid) I was going through from sketch to the final drawing.
I admit, if only I had some more time I would keep on going and add some more details).
Phase 1: Sketching with my tablet straight to the computer, trying to get an interesting form while keeping a clear silhoutte as possible.
Phase 3: Adding more details and especially shadows and highlights.
Phase 4: Smoothing the shadows and highlights and tweaking the saturation and hues.
Phase 5: Combining the background and adding little effects to better the composition