Start with scope and scale.
Before you make objects like diagrams or maps, spend some time determining their scope and scale.
Scope is your clearly stated purpose for the diagram. The scope of a blueprint for an actual house is greater than the scope of a diagram explaining the rooms that make up a typical house.
Scale is the relative size of your diagrammatic work.The scale of a map covering a wall is greater than the scale of a map on regular-sized paper.
To think through scope and scale, ask yourself: