TPBO

[Sumpter250]

I've pretty much settled on doing a freelance industrial spur along the lines of what some others have done, but which could also possibly be treated as a separate short line.
I know what industries I want on the layout and the era (late 1970's-early 1980's) - got all sorts of equipment to operate on it and plenty of Peco turnouts and flex track running out my ears, but.... About all I've done at this point is lay temporary track the length of my benchwork (20ft) and put a couple of sidings on it just to have something to operate those sound equipped loco's I've acquired and do some simple switching.

If your industries aren't built yet, start there. Leave your temporary track in place and play, while the structures are being built.
As each structure is done, place it on the "layout". At some point there will be several structures on the layout, that you can move about, and lay temporary sidings to.
Then, with a little research, you can think about what industries should never be close to each other and insure you don't have that going on. get all your structures placed in a pleasing arrangement.........and then lay your track to fit the "topography".....kind of like what happens in the prototype world. ( some slight building movement can be done where adjustment is required to ease a curve, or lengthen a siding. )
Personally, I believe that planning, in some cases, is highly overrated.( see how quickly plans changed on my "new modules" )
It's far more interesting, when a structure is "oddly shaped",or even exists, because of the shape of the available property. This natural and common adaptation is almost impossible to "plan", and lends a touch of reality to a modeled scene. The simple placement of structures and "seeing" the area around them leads to setting the "real estate" that your trains will have to move through. Grades, rivers, highways, etc. all affect the placement of track, and, if in fact these things can cause the track design, it will look all the more realistic.
A working track plan, and a plausible environment, the end result of "playing with all the elements" ( and the fun of playing as it all happens. )