I actually have a book by Shepard Paine, it's been really helpful. I've mostly been combining stuff from that book and things I learned in my museum classes. I'll definitely look up Ken Hamilton.
Today I covered everything in a thin layer of plaster, then did an earthy paint as an undercoat. While the paint was still wet I dusted it with some Real Dirt from the backyard and shook off the excess. The dirt actually got really good coverage. I did all this outside, so please forgive the ever changing lighting in the pictures.
Added some highlights and lowlights with a mix of railroad scenery earth stuff.
Four different colors of turf, terrain and shrubs added and logs. The chewed up pieces of wood were old toys from my chinchilla's cage. He thinks a bundle of sticks is the most exciting thing in the world. I thought that his destruction of them gives the wood a natural look since the the trees are victims of Terrible Forces of Evil. The glue is still drying in the picture, so ignore the little white globs.
Still need to add people, vehicles and the Terrible Forces of Evil.
Not quite sure how to transition the edges of the diorama into the base though.