Your book writing format starts with structuring what you are going to say. Whether this will be an opening précis or a full outline, if you don't start from an organized format, it may be difficult to reorganize your book later causing a great deal of rewriting.
First, what information does your reader already have? Knowing this will help identify your audience before you put the first word on the page. Make sure you state up front what knowledge and expectations you expect your readers to have; this will tell them what they need to know to get the most out of your book.
When structuring what you write, you should focus on: "What questions should I expect the reader to be asking at each point?" This is particularly useful when writing books designed as self-help references or as teaching manuals.
Next, explain conventions you'll be using. Most non-fiction books are technical writing at their finest; they cover a topic in considerable detail. If you use special terminology or technical lingo, or you have code examples, or formulas, explain how you're going to cover the information and make pertinent lingo stand out.
Then, begin to structure your outline. Unlike a novel, a non-fiction book needs to be formatted not just for linear reading from beginning to end, but also for people to dip into chapters of interest as a reference.
If you're doing page layout yourself, use a .5" margin, which will guarantee a clean edge to your bound book. When formatting your book, don’t forget to focus on things like using header information properly; use Header 1 for each main header and Header 2 for sub-headings. This will help you create your table of contents.
When the book is finished, let it sit, and then begin a daily ritual of reading one chapter each day—starting with the last one, and working towards the first—and highlighting terms to build the index. More information on organizing and formatting your book will be available in our soon-to-be-published book, How to Organize Your Non-Fiction Book: A Workbook for Authors.