Here's my quick study (as far as I will take it for demo's sake)..
From a Painting standpoint, here's how we need to think of it. The simpler, the better.
From a Drawing standpoint, here's how we get there..
-Think simple first... a cylinder or a box next to another one.
-Then get to a comfortable point where we can adjust/modify that box or cylinder.
-Once the base is there, think of the other features as miniature forms.
-Refine and start pinpointing the corners of those forms.. more importantly, where they lie on the bigger picture.
-Now it's possible to design the shapes...
-..until we have our Refined Lay-In.
The rest is a combo.. back and forth, from drawing, to painting, to designing/abstracting, and repeat.. and repeat...
Hope it helps :)