The first thing that bookstores look at when deciding whether or not to accept your book is the formatting. Bookstores expect all the books they sell to adhere to publishing standards, and sometimes those standards differ between fiction and non-fiction books. For example, in fiction books, new chapters can start wherever they fall, but in non-fiction, new chapters must start on the right side of the book.
Bookstores are also looking for books with correct registration. Your book needs an ISBN, and we highly recommend you register it with the Library of Congress. This lends you credibility with the bookstores.
Finally, you’ll want to have endorsements on your book. You may not be able to get a well-known author or celebrity to endorse your book, so reach out to other authors who are at the same stage in their writing careers as you, and request to trade endorsements. You can even use endorsements from your friends and family if you need to.