If you flood your audience with a series of books all at the same time, they are more likely to buy the newest one and ignore the previous one unless you maintain momentum on promoting both books at the same time.
Authors who work with a traditional publishing company have a team of people who will help you make this decision, so if you are interested in the answer then I’ll assume you are a self-publisher and my answer is specifically directed at self-published authors.
I recommend that you wait to release the second book until you have an automated book marketing system that allows you to consistently promote the first book while you write, publish and promote the second title. Your sales from your first book should not have to suffer because you don’t have the time to devote to it anymore now that you have a new title.
If you don’t want to develop an automated marketing system, I recommend that you at least wait until you break even. The exception to the rule is if you have someone willing to sponsor the publication or buy a large quantity if as soon as you release the new title.
This approach is all about stopping you from spending more money before you master marketing and sales well enough to recover the money invested on the first publication. If you have poor sales for your first book, a second, third, or even fourth book is not likely to solve your problem-it will only add to your total debt.
Book marketing expert Brian Judd recommends that you start marketing each book at least 6 months before it is released. So if you want a specific number to go by, you should wait at least 6 months after the release of the first book to release the second. This is especially true if the topics of the two books are different. You may be able to get away with a shorter wait for the second release if the topics are similar.
In fact, if the topics are similar, it is likely that the sales of the second book would boost the sales of the first-especially if you mention the first title inside the second book so that your new readers know about it.
Question: Do you think it is a good idea for an author to write books on more than one topic?
Image by: Marcus Quigmire from Florida, USA (Time Uploaded by Princess Mérida) [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons