Metroman,
A lot of it comes with experience, constantly doing your homework, networking and some good ole trial and error. :D
In addition to PP, we do a lot of demo & rehab work. So over time I developed an "eye" for it. I figured out how to properly load my trailers and dumpsters to maximize their use and to keep the costs down. There are all sorts of "tricks to the trade" or "methods to the madness" one picks up on/develops over time. :cool: