Here's a <strong>20-point checklist</strong> (PDF format) from the world's highest paid copywriter, Clayton Makepeace.
And here's a <strong>blog post explaining the 20-point formula</strong> in more detail from a copywriter Clay hired (Roy Furr).
Here's Roy's book on story-telling: <strong>Amazon link</strong>.
I haven't purchased it yet but I am subscribed to his newsletter... he delivers an insane amount of value... for free... in prolific proportions.