There are various books out there on moving from dissertation to book, but in my opinion these are the 2 best (links to Amazon):
1. Beth Luey, Revising Your Dissertation: Advice from Leading Editors, Updated Edition. I actually read this book BEFORE I started writing my dissertation, and it helped me avoid some major mistakes the first time around.
2. William Germano, From Dissertation to Book (Chicago Guides to Writing, Editing, and Publishing). This book contains lots of good advice, but be aware that he advocates for some people NOT publishing their dissertations.