Sketch the big idea
Use boxes, labels, and simple arrows to show the main surfaces and relationships. The constraint prevents premature debate over typography, spacing, or pixels.
Pair sketches with decisions
A sketch should answer a product question: where does the user start, what do they see, and what action changes the state?
Leave room for builders
The sketch gives a team a direction, not a frozen interface. Combine it with scope boundaries and a hill chart so progress remains about understanding, not mockup completion.