Perfect is a high bar. It all depends on the product and target market, but there are time-tested guidelines for effective ad copy:
Focus on benefits over features. Answer "what's in it for me?" from the customer's perspective.
Speak to a specific pain point using the customer's own language.
Create an emotional response first, then provide rational justification.
Lead with the most compelling hook.
Eliminate every unnecessary word.
End with a clear call to action.