Before beginning any design process, have a purpose for it. An elaborate narrative isn’t necessary, but some concept of why this design exists should be developed. This step is critical because it creates a realistic design viewers will buy into. A backstory gives context as to why it was made, who made it and for what purpose. This helps you naturally evolve the design.
For reference, covered 19th-century wagons are my starting point. Though the final design will bear little resemblance to a wagon, I want it to carry the essence of one. I divide the morgue into sections, using Mischief’s Pins feature. The canvas is virtually infinite in size, so you can space the groups about, set them with a pin and jump right to them.