Official rules are the contract between you and every entrant, and a thin or missing rules document is the fastest way to turn a promotion into a dispute or an FTC problem. The federal baseline itemizes the standard skeleton, and the compliance checklist turns it into a printable list.
At minimum, the rules should state a clear "No Purchase Necessary," an Alternate Method of Entry with equal dignity, eligibility (age, residency, and exclusions such as employees and void-where-prohibited), exact entry instructions for every method including entry limits, and the start and end dates with time zone.
Then the prize details: a complete description with the Approximate Retail Value (ARV) of each prize and how many are available, the method used to calculate odds (or the odds themselves), the winner-selection method, the notification procedure, and any deadline to claim. Finish with the sponsor's legal name and physical address.
The tax statement belongs here too: winners are responsible for taxes, and you'll generally file Form 1099-MISC for prizes of $600 or more. If you promote in Canada, the Canada notes add a skill-testing-question requirement and the Quebec-specific considerations under Bill 17.
Write the rules before you promote, not after someone asks for them. A complete, linked rules document is what makes the rest of your compliance provable.