deconstruct the scene by breaking it up into modular pieces in your mind. environment artists will plot out regions over the reference image like this to help get a better approximation.
Comming soon: helmet and add-ons. Two of his guns, I'm supposed to make it 'upgradeable', or 'modular', so there's the base gun, and the top changes to other things.
Screenies from latest freelance project that I've rounded off; Meridian Line. Highly modular geometry and textures designed to procedurally snap together.