Start by defining the exact message decision: headline, value proposition, pain angle, proof point, CTA, category narrative, or campaign hook. Add current copy, page or campaign goal, target persona, buying stage, traffic source, constraints, and the business reason this decision matters. Write a decision rule before testing, such as “ship the version with strongest clarity and credibility among economic buyers” or “select the variant that best explains the new category.” Store the brief in Airtable with owner, due date, reviewers, and final decision status. If the test cannot change what will actually launch, do not run the sprint.