The brief, in three parts. Then the outline writes itself.

Write it the way you would say it out loud. You can change everything later.

Or start from one of these

• How a first-time manager runs their first ninety days: what to do in week one, what to leave alone, and how to tell whether the team trusts you yet.
• Watering a balcony garden: matching water to the pot, the sun and the season, for someone with a handful of pots and no gardening experience.
• Pricing freelance design work by the project instead of by the hour, including how to write the estimate and what to do when the client asks for more.