The free audit that is actually worth receiving
The free audit is the most common sales tool in SEO and the most commonly wasted one, because the person sending it optimises for looking thorough rather than for being useful.
Three findings, not thirty
An automated report with a hundred and forty issues communicates that the sender ran a tool. A short document with three specific findings communicates that a person looked at this particular business.
Choose the three by business impact, not by severity score. A missing meta description is a real finding and an irrelevant one.
Connect each finding to money
A prospect does not care that their site has a crawl depth problem. They care that their most profitable service page cannot be found by customers searching for it, which is the same fact expressed in the only terms that matter to them.
Every finding should end with a sentence starting 'which means'. If you cannot finish that sentence, the finding does not belong in the document.
Leave the fix incomplete on purpose
Show what is wrong and why it matters. Do not supply the full implementation. This is not manipulation, it is scope: the diagnosis is free and the treatment is the engagement.
The strongest close is usually the honest one, which is telling the prospect which of the three findings they could fix themselves this week and which one they should not attempt alone.