There is not a recipe to write, every author has is way, but obviously you have to adapt the thesis format and transform it in a book because the way the university ask to present thesis is really different when you want to put in a book, mostly because your book have to be interesting to others, not only for an expert panel.
In the other hand, I recomend you after you write to ask about revision for an editorial, in the mayor cases they review the material with people that write books and give some corrections to you to make the book better. Of course you have to define your market to know the focus they have to look for.
I am promoting an editorial/consulting company in this topics, we are new in the market but you can take a look on the web page: www.highrateco.com
Some of the best ways to follow and get to writing what you consider "the best book" are: 1. Listen to the inner voice of your deepest thoughts, or deepest needs, or deepest yearnings or what moves you with such power that you can't stop feeling it in your soul. 2. Identify the best of your obsessive passions linked to one, some, or many of the above from deep within your subconsciousness as it or they grip you, which you become aware of only in your moments of deep solitude and deep thoughts or deep rapture. 3. Cultivate a habit of writing down sudden flashes of intuition, or idea, or "hunch" about an issues that comes to you in unexpected moments. 4. Follow up what you have under these circumstances and develop it into a thesis, or headline or topic for a potential book. 5. Start writing once you get into the mood, and if you can't get into the mood, force yourself to keep thinking about how you want to write a book on what you are focused on, till the moment comes when you are pushed into actual need to start writing the book. 5. Keep writing and writing everything that comes to you on the issues you are focused till you are exhausted, then stop and wait for another day or time or moment. At this stage of your first draft, do not worry to much about grammar and correctness, just get the whole thing down. 6 Your moment for grammar, correctness and editing comes after your book is written, then start cross checking, researching, confirming, acknowledging, etc, depending on the type of book you want. Let me know how useful this is to you, for me to see if if I can give answer to your question on the difference between thesis and Book.