Writing a book can be a great way to promote your business. If you are truly knowledgeable about your industry, or a certain niche in your industry, then you have expertise you can share. If you are willing to go out and interview a bunch of people about some area related to your business, you will have interesting material to share. Even if you just devote some time to researching a specific topic, you can become an authority on that subject and have information to share.
Authoring a book positions you as an expert. There's something about a book that impresses us, even in this age of blogs and texts and Kindles. The assumption is that if you wrote a book on the subject, you must know what you're talking about.
Clients like working with experts. It makes the purchase decision much easier for them, because you've already been validated by the publication of this book.
Here are a few things to know, before you start writing:
1.) You will probably not make money on your book. In fact, it's very unlikely. It's more probable that you will spend money on your book, especially if you decide to aggressively promote it. Think of the book as visibility for your company, and not as a moneymaker.
2.) Don't plug your business in the book. This is not an advertisement. This is about informing and educating and maybe even entertaining. Stay focused on what the reader wants to know about the subject matter as opposed to what you want them to know about your company. That's not to say you can't mention your company. Examples from your own experience can be useful in the text. Just make sure you're not beating them over the head with a sales message.
3.) A book doesn't have to be that long. I've spoken with some business owners who are intimidated by the idea of writing an entire book, but a book might be shorter than you think. In fact, shorter is sometimes better. Your audience may not be interested in reading a business book the length of "War and Peace." Maybe you should shoot for more like 60,000 words or so.
4.) You might spend more time promoting your book than writing it. For my book on women entrepreneurs, I backed myself into a tight deadline with the initial manuscript and completing it on time became a Herculean task. I had the idea that finishing the manuscript meant reaching the finish line. But oh no,that was just the beginning! I spent the next year and more promoting the book, even after the lengthy edit process that followed the initial manuscript. I hired a book publicist from a big firm in New York, and still the promotion ate up hours and hours of my business day for months on end.