Excerpt from: What is a designer by Norman Potter:
Ask yourself:-Why this document or drawing or model?
-For whom and to whom from whom?
-In what time and place and occasion?
i.e.:-For what purpose, with what intention, with what (precise) aim?
-or for which of several purposes seen to be related?
Then:-When should it be done and when conveyed? (may be separate)
-How it should be done? (less a question than an answer)
Thus:-Why - Who - What - Which - When - How
Embrace:-Context, relevance, completeness, sequence, tone, consistency, usage, and other things you may wish to consider.
Thus giving:-Relevant form to what you do.
-From the possibilities of mode, vehicle, medium, agent, intention.
-Each of which can usefully be distinguished: they are not the same nor better described as dualities. (medium:message)
The Apparent case for navigation by principle.