Next, I did a quick black and white thumbnail sketch of how I wanted the light and how much I needed to extend the canvas. I use this time to finalize my thoughts about the concept behind the piece. I'm thinking a standoff between organic vs. mechanical crab-like walkers; when the tools that brought them into the fight will ultimately fail them. I really do feel sorry for the guys in the mecha.
Then I built a quick 3d model to scale using primitives. I'm really taking the time to get the camera angle and height just right. Using the model, I can immediately see the flaws in the original thumbnail. Finally, I start painting!