How are you writing prompts that don't spit out generic marketing copy?

Generic in, generic out. The copy gets better the moment you feed it material it couldn't make up itself. What I paste in now: a few real customer quotes (reviews, sales call notes, support tickets), the one specific claim the product can back up, who it's for in one line, and two examples of copy we liked. Then a short list of banned words, because otherwise you get "elevate", "seamless" and "unlock" in every draft. Ask for 10 short variations rather than one polished version, pick the two closest, and tell it what's wrong with them. The second round is always better than the first.