[icedchai]

The biggest mistake is not knowing your audience.

Is the diagram for marketing? A sales proposal? A business person using the product? Technical peer?

If you don't know this, you don't know if you have the right level of detail.

[pinko]

Underrated comment in this thread, which is full of asserts of universal abstractions and patterns which are not universal. (And of course this insight applies to all kinds of written communication, diagrammatic or prose...)