I’ve had a small number of books published and also self-published three under my Aero Vintage Books company. In my limited experience, there are two things that will hinder self-published books: distribution and promotion. Trying to get the books into catalogs and bookstores is very time consuming and frustrating. Most sellers are only going to use the major distributors and they just don’t want to mess around with a few titles.
Advertising is crucial but very expensive. It will eat up profits quickly. It seems like you can sell books if you advertise but you spend your income on the advertisements. Having a website is good for sales, but there are an awful lot of aviation books out there, with more coming every day. There is much competition for a limited number of dollars (or pounds). If you have a great book that is well produced, and it hits the market right, you will make more money self-publishing than you will if you go through a publisher. However, you need to be the 1 in 1,000 that hits the market right. The odds aren’t good.
Don’t deceive yourself that the book will be a bestseller just because you are interested in the subject. Unbiased market research is critical; a gut feeling doesn’t sell books. One book I did, “B-25 Mitchell in Civil Service,” has a very narrow niche market and it sold appropriately. Guys who had the interest and bought the book thought it was great (and it is!). However, it won’t sell as well as a book on the B-25 in general. I’m still selling the B-25 book, but I also have alot of money tied up in the book that only trickles back. It will take another year or two to sell the title out. This book was published nearly seven years ago with a 2,000 copy print run. On the other hand, we did a DC-3 book that sold out 2,000 copies within two years, and the three authors split about $20,000 net.
Do your homework, and don’t be optimistic. Stay current with the reality checks.