When I wrote my first book it never occurred to me I would write more. I am glad I did. While my first book sells well and has sold more copies than any other book I have written, it is a good thing it is not the only title in my list.
Last year the book in question sold more copies in print and Kindle versions combined than any other title I have. Yet in terms of total dollars, it only accounted for 30% of my sales in the last 18 months. The last 12 months have been the best in terms of sales and revenue generated since I began self-publishing.
70% of my sales come from all of my other titles. Some titles sell very well, either as paperbacks or Kindle books. Other titles only sell a few single copies a month or a single copy every so often. It all adds up though.
Because of the low cost entry into self-publishing made possible by CreateSpace I have been able to keep my cost per title to produce as low as possible. Every book I have self-published except two have at least recouped the money invested to get the book into print. That is probably a better record than traditional publishing houses.
Print-on-demand and Kindle books allow authors to get their book to market with the lowest possible investment. Having more than one title allows an author to have multiple revenue streams from books sales.
Another advantage of having multiple titles is readers who purchase and read one book and enjoy it or find the information contained of value will purchase other titles by the same author.
Books mature over time, saturating the target audience. Non-fiction books become out-of-date as time passes, making the content of little value. While this is not true for all books, it is true for many. Having a well developed back list lessons the impact of a star seller falling in the sales totals.
All too often authors forget publishing is a business. For self-publishing authors who desire for their publishing venture to be profitable, developing a back list is an essential step towards profitability over the long term.