There are several potential benefits to publishing multiple titles, especially if the titles are similar:

• When customers see that the author has written several different books, it creates the perception that the author is a serious, dedicated writer. When the author only has one book available, the perception is that this is a new author.
• Customers who enjoy one of your books are likely to try more of your books. There is a big IF involved here—i.e. how likely are customers to enjoy your books? If so, having multiple titles out can earn you repeat business.
• The books that have been out the longest are likely to have more reviews, which can help lend credibility to your newer books even when they don’t have reviews yet.
• You can build a fan base among your prior customers and utilize this to help create buzz and initial sales for your new books.
• When shopping for print books, customers often buy a few books at a time. One reason is that customers may qualify for free shipping this way; but even without this incentive, multi-book shopping is still common for print books. The more books you have available in print, the more customers are likely to buy a few of your books at the same time, especially if you have similar titles. (If you have an omnibus for a series, you can discount it to offer an incentive to buying the entire set up front.)
• Your own books are likely to show upon on each other’s Customer Also Bought lists. This way, sales of your own books help to inspire same-day or future sales of your other books.
• If the titles form a series, the further along you are in the series, the less risk readers will see in the time they will invest. When only the first volume is out, there is a greater chance that the series won’t be completed. (If you have two different series out, but neither is finished, this may be a deterrent. Readers may wonder if you don’t tend to finish what you start.)
• The more books you publish, the more experience you gain, which gives each new book potential for improvement.
• Working on your next book will keep you from checking your stats too frequently, take your mind off reviews, and give you an incentive not to waste your time.

More and more authors are becoming aware of possible benefits of the multi-book strategy.

This news leads to a few common mistakes:

• The temptation to hurry. Rushing the writing and rushing to get the books out there, with the hope of multi-book success, may backfire. Delivering quality content is much more likely to earn referrals and good reviews. A lack of quality due to a rushed delivery is much more likely to earn bad reviews and no future business. (You can revise a book to improve it, but you only get one chance to make a good first impression, your reputation is at stake, and bad reviews are there to stay with print books.)
• The temptation not to market. Authors may hope that the benefits of having multiple books will make up for a lack of marketing. There are two ways to look at this. First, consider that if the books aren’t selling, the lack of reviews and dismal sales ranks will discourage sales even more so. Second, consider that every customer you attract through marketing may buy multiple books in the long run. Therefore, if you plan to write multiple books, you should be more motivated to market because there is more potential gain in the long run.
• The temptation to create a larger number of shorter works. The problem here is that customers want a good value for their hard-earned money. If customers feel that the content isn’t a good value, they are less likely to provide referrals, repeat business, or good reviews. If they feel that it’s a poor value, bad reviews are more likely. (This is on top of being less likely to buy the book in the first place because it doesn’t seem like a good value, let alone try out a new author.) Just to be clear, I’m not saying you should price your book cheap (most books should avoid the minimum price point—here is another common mistake, but that’s for another day). Rather, I’m saying that providing full-length books may be better than a series of short stories.

The first books you publish help to establish your reputation. You want to start out with a good reputation as a professional author who delivers quality content. You want to give your first books the best possible chance of earning referrals, repeat business, and good reviews.

Satisfying customers is the key to long-term success.

If you have the motivation and diligence to write and publish several books, then you’re obviously interested in long-term success. So take the time now to give your future its best possible chance of success.

If you have the motivation and diligence to write and publish several books, market your books avidly from the beginning in order to derive the greatest possible benefit from your efforts. You have more to gain from marketing in the long run than an author who only writes one book, so you should be more motivated to do this.

On the other hand, there comes a point where the book is excellent, but if you’re too much of a perfectionist, your book may never get finished. The temptation to rush is much more common than to continually delay because there is always something else that could be improved. However, if you’re one of the perfectionists who may take forever to get your book out there, then you have the opposite problem of needing to say that enough is enough, it’s already very, very good. It helps to have pre-readers who can help you judge this (since thinking it’s very good when it’s not good can be a major problem, while thinking it’s not good when it’s already excellent may be an unnecessary delay); however, getting honest feedback is another issue, too.

Chris McMullen, author of A Detailed Guide to Self-Publishing with Amazon and Other Online Booksellers, Vol. 1 (formatting/publishing) and Vol. 2 (packaging/marketing)