How do I kindly point out mistakes or offer a rewrite when asked to critique someone’s work?

Q. A local husband and wife lawyer team forwarded a letter regarding elder law that contained some good “points,” but lacked spark along with misprints, poor punctuation. How do I kindly point this out and perhaps offer a rewrite?

A. Just approach them and be upfront, yet diplomatic. ”Got your letter and it looks like a great service you’re offering. And I know your goal of sending out such a piece is to drum up business, and as a professional marketing writer, I couldn’t help but notice some ways to really improve on it, which in turn, could really increase your response rate, and ultimately, your bottom line. I’d love the opportunity to discuss this with you…” etc… It’ll either fly or not and if not, nothing ventured, nothing gained. You could do it by mail or email – your call.