This is something I've learned recently. If ever I'm stuck on how to paint a particular background for a shot. I try painting it from the opposite direction. This doesn't mean it is uncomposed, it just seems to me that I tend to put all of the interest right in front of the "camera" so to speak, and everything behind it is rather simple. This is really great when I'm struggling to figure out how color is going to work in a scene, or something like that.
If I've learned anything from the Robo-san project, it's that nothing is simple, nothing is easy, unless you really make it so. You could paint a completely barren desert landscape and it could still be intensely complicated if you were really trying to construct a believable space.