Confirm that the manuscript has a clear beginning, middle and end, and that all chapters are in the intended order. Resolve obvious duplicate passages, mark sections still in progress and make sure notes to yourself are not mixed into the reader-facing text.
Prepare a short brief that names the intended audience, key goals and concerns. Include source notes for facts or quotations and identify spelling choices that must remain consistent. A clean handoff saves editorial time and gives the editor a clearer view of the book’s real needs.