Painting is hard. I mean... I create concepts, matte painting and stuff like this for a living - and I still think its hard. Sometimes, when I have enough time, I start my paintings from scratch, based on a hand drawing or just painting directly in Photoshop. When time is short, however, I make use of 3D models for the base and paint over them.
This timelapse video shows you the process of how I used Blender and Photoshop to finish an artwork in about 6 hours (sped up to 30 minutes).
Commented tutorial coming soon!