The curse of knowledge

Forgetting what you know.

The core problem

Once you know something, it is very hard to imagine not knowing it. Most unclear explanations are written by someone who has forgotten which step is not obvious.

State the context before the conclusion for anyone who was not in the room.
Ask what the listener already knows rather than assuming.

Checking

Have the other person restate the plan in their words. It takes fifteen seconds and catches the misunderstanding that would otherwise appear a week later.