Taking some advice from Sholto who's Blog has an excellent looking board that has inspired mine heavily, I started with laying out the main street network for my 4x4 Drop Zone Commander board.
Now each city block within the road network will be built with a combination of roads, buildings, and whatever other scenery comes to mind.
One finished example:
From another angle:
This system is incredibly easy to do, and, compared to many other terrain methods, pretty inexpensive. I recommend it.
P.S. I may or may not have toyed around with some Battletech miniatures in here as well ;)