Back when I wrote my first three books, I used Word and hired someone to format one of my books. Getting a book from written form into .epub and .mobi formats was a hair-pulling experience for me. One day, thanks to Chris Brogan, I was introduced to what I think is the most amazing writing and publishing tool:
Pressbooks is a writing/publishing tool based on the Wordpress blog platform. If you use Wordpress for your blogs, you'll instantly feel at home with this tool. Pressbooks organizes your book with front matter, chapters and back matter. You can easily add pages and switch around chapters. It automatically creates a Table of Contents for print and it is clickable in electronic formats, allowing readers to instantly jump to chapters. You can add pictures and resize them. There are several themes to choose from which will provide design and formatting for your book.
I published my fourth book, The Passionate Lives of Deaf and Hard of Hearing People using Pressbooks and it was so incredibly easy. The export feature packages the book into .epub, .mobi and PDF files. I can jump from book to book within the software and everything is completely organized.
I am now working on my next four books using Pressbooks and I can't imagine using anything else.