Proposals have been somewhat of a mystery to me but this is what I have found publihsers want in a non-fiction proposal.
1. Cover letter- Contains title, author byline, and contact information
2. Proposal contents – This has the table of contents
3. Overview- This has the summary of your book and what the “hook” is. Why someone wants to buy your book.
4. The mareket – Who will read your book?
5.About the book- This is the area where you give a detailed description of your book.
6. The competion – What does your book have that others on the market don’t?
7.Biography – Describes you in the best light possible.
8. Chapter summaries of each chapter
9. Word count, if it is complete, or when it will be completed, format, etc.
10. Promotion- Have a promotion plan for your book.
11. Attachments – Follow the guideline as far as what they would like you to attach.
Hope that helps. I wish you all the best.