You will have your manuscript professionally edited ultimately, but you can do a lot yourself with time and distance to self-edit and then rewrite as needed. Work on a chapter, print it out, and read it in the context of the other work you’ve already done. Then move to another section and keep working back and forth until you feel as though you’ve done all you can.
You will probably continue to add to and subtract from your manuscript for weeks. You’ll think of new things to say or things you’ve previously forgotten as you read and reread. You will decide you haven’t said enough about one topic but have gone into too much detail on another. So save that extra material for speaking engagements or another book or article.
If you have the time, put the manuscript away and work on other things for a month or more; then come back to it with new experiences and a fresh eye.
With distance, check to see whether you’ve told a story, the manuscript is balanced in terms of the numbers of stories and the way you’ve told them, the subject matter is compelling and interesting, and the writing pulls you forward so you want to keep reading.