I've been meaning to do a good realism study from photos. I don't like taking more than a few hours to do something, but I forced my self to spend some time to think this through. So after doing several attempts that made it hard for me to be quick and accurate with my proportions. I devised this interesting method of really separating it into segments. The more I thought of it as segments and individual shapes. It was much easier to draw something complicated, in a short amount of time. Once I nailed a good section I'd merge them down to have good layer management. The method was fun.
I think the point of why this worked for me, is it kept it simple. Also, the fact that each segment that was broken, created a strong hard edge. So it created nice and clean separations without excessive noodling and correction. The next step is to do this again and find a way to design and even finish paintings with a more of a realistic vibe. Anyways I hope this gives some insight. I learned alot, especially about how real strong shapes and values go a long way. :)