Choose a reader and a decision
A brief should say who the piece is for, what they already know and what they should be able to do afterward. Those three details are more useful than a target word count on its own.
Collect evidence before drafting
Gather examples, sources and the people who can verify factual claims. Decide which observations are your own and which need attribution. Keep promotional claims out of the draft until someone can support them.
Plan the second life
Assign an owner and a review date. Notice which questions readers still ask and use them to improve the page. Updating an existing explanation can be more valuable than publishing another article that covers the same ground.