Notes:
I have found this method for building worlds to work for me. Other developers use other methods that are not too dissimilar. I use 4 steps in the building of worlds.
The Design step lays out (on paper) the major aspects of the world. This step is refined until I am able to start the modeling work.
The Modeling Components step is building all of the major models needed for the world.
The pieces are put together with the necessary interconnections in the Assemble step.
Finally, I work on optimization and clean up.