Newbie layout setup

All,
I have just gotten into the model railroading hobby w/ my 3 sons. I have a 3-rail O guage layout around the top of their bedroom (12’x18’). It is a two oval layout w/ 4 switches to allow the trains to switch tracks. I am now in the process of trying to figure out the best way to wire the layout. Since I don’t have much experience w/ this I wanted to see if anyone had suggestions on where to place decouplers, insulators, etc. that would best use the design. I have a diagram that I drew if you would like to take a look.

Bryce
trains@timberlakes.net

PS. I am trying to fini***his by Christmas. They currently have only a single engine so they manually switch the engine. I just bought them, on Ebay, a Lionel CSX SD-80 (model 18296) and would like to have it all working for them.

I cant help other than I would suggest reposting this on the Classic Toy Trains forum as they are the real experts with lionel 3rail.