The book you publish is almost never the book you started writing. I discovered an easy way to make very successful bearings using Teflon tubing, and went to town and designed at least a dozen engines that used the new technology. It seemed feasible at the time to put them all in the book. The scope of this idea was far too broad to be practical. Most builders probably only want to make one motor anyway. But I want my readers to find value in their purchase, so I maintained an approach to publish a collection of designs, but downsized it from 12 to 4. The 4 designs are all very similar, and the final product of these projects is a traditionally configured motor. The aim is to provide the builder with several choices for building a conventional looking motor.
It is hard to guess what will be relevant when writing for a small niche market. The first rule is to make it relevant to yourself. The second rule is to make it understandable to your audience. Financial success occurs when you are able to connect your audience with the book. And that is the role of marketing. Good marketing puts your book in front of your potential customers so they see it as one of their choices as they invest their time and energy into the same subject you are writing about. And if they choose to buy it, they find it relevant and understandable. That success will lead to positive reviews, broader discussions, and more sales.
Successful self publication is much more complex than it first appears. Think for a moment about the tasks a publishing company performs with and for an author as a book is developed. The publisher may provide editorial direction, proof reading, editing, formatting, illustration artists, cover design, market research, marketing plans, advertising, press releases, book tours... It's a long list, and it keeps on going. When the book is finished and ready to sell, the work is about half done. It has been my experience that I can invest as much time and effort into promoting a book as I spent writing it.
If you are going to write and publish a book yourself, and if you want that book to be successful, you need to become the manager of the publication process and address all those tasks that a publishing company would do for you. You may want to do it all yourself, but few people have all the skills needed to produce and market a good book. That is why even independent self publishing authors routinely solicit help from others.
Nothing illustrates this better for me than proof reading. I have already fixed a few typos and spelling errors in this article, and chances are I will not catch them all. No matter how many times I read through my own work, I never catch all the mistakes. So for me, effective proof reading means that it must be read by someone else.
For my first endeavor, I recruited five friends and gave them each a copy of the book. I did this after I did multiple read-throughs myself, and I was pretty sure it was near perfect. The results of that effort not only brought me lots of good feedback about the book, it taught me a few things about proof readers.
My book, it turns out, was far from perfect. One of my proof readers was very skilled in the art of grammar (it is an art form, you know) and gave me incredibly good advice that improved the book. And he didn't have to read the whole book either. He told me "make these kinds of changes throughout the book" to improve readability, and he was right.
Among the other proof readers, one was reluctant to write in the book for fear of defacing the book or perhaps didn't want to appear overly critical. A couple of them said they didn't really understand the technical subject matter and were reluctant to finish it. Each time that I have used this social networking approach for proof reading I have found very valuable feedback from one or two of them.
I simplified my process with this most recent book. I first did several cover-to-cover readings myself. When I knew I had caught all the mistakes I could see myself, I asked my wife to read it. She is not into this technology stuff like I am, so her feedback was very good at finding places where I needed to simplify and clarify my approach. Then, instead of recruiting five friends, I just went to one of my previous volunteers who had done a good job before. I gave him a galley proof of the book with a $100 bill as a book mark, and told him he could keep the book mark as a souvenir for his efforts. We negotiated a timeline and he was done in a couple of weeks. He didn't have as many changes this time (I must be getting better) and I have confidence that my $100 investment is well worth it for the peace of mind I get in return.
Self publication doesn't mean that you are doing everything yourself. You may have to become your own project manager at times. You will always improve your product if you recruit help from people who have the skills that you lack.