Start with
what’s true.

Who already buys this service, what problem triggers buying, and what they want to do next.

Name, deliverables, price, billing, timing, exclusions and refund terms. Write unknown where a fact is missing.

Where should a ready buyer go? Name the page, what they do there, and what happens next. If you do not have that page yet, write unknown.

Results, samples and quotes you may use, plus anything withdrawn. None is a valid answer.

Style, prohibited claims, colors, imagery you can use and the channels you actually use.

Why promote now, real deadlines, audience permission, capacity and owner time. No deadline is a valid answer.