Starting inspiration: Playing the game "World of Tanks", crossed with my childhood adoration of the War, and tanks in general.
This was the 'finished' piece. After some more tightening up, I applied some Hard Light gradient overlays, to get a play between warm and cool colours, creating a nice juxtaposition.
And that's it really. I still have a stupidly long way to go, and each step is painful with digital art, but I *will* get better at it.