I've written a lot about building and using planning models. A planning model is a small model of a model railroad.
The book I go to for many small structures is A.G. Smith's An Early American Seaport. The book is out of print but still can be found through used book dealers and at train shows. There are many other books like this one featuring other architecture and building styles.
I scan the pages, reduce them to the size I need, print them out, glue to a cardboard backing, and build them.
Here's the 1/2" scale planning model I built for the Sea Port display. The little structures are place holders showing the size and scale of a building in the scene. These can be moved around or removed to help determine how the final display will look.
This is a valuable tool to use when trying to project your ideas to someone who "doesn't get it'". It's also a great "what if" tool.
Here's a more elaborate planning model of an 8' by 25' Lionel layout. The project followed the model closely.