I found this FAQ at BlackDogPublishing, and I thought it was well thought and written.
Sales is not the only metric for your writing. Lack of sales isn’t attack on your writing skills.
No one is buying my self-published book, can you help?
Marketing is by far the hardest part of the book industry at present. This isn’t because of any failings on the part of the author, agent or publisher but simply because of how unbearably saturated the book market has become. The rise of self-publishing has been both a blessing and a curse. The positive side is that it has allowed authors to publish themselves and allowed small presses to survive by making use of print-on-demand services. The negative side is that this means millions of authors have simply published themselves and the possible profit margins grow slimmer each year as a result. The regrettable truth is that this has left many authors and publishers with completely unrealistic expectations of how well their books will sell. Some even take the shrinking market and the lack of sales and engagement their book attracts as an attack on their writing capability. Think of a sandwich shop, you could make the best sandwiches in town but if there are 6 million other sandwich shops on your street it’s going to be difficult to convince customers your product is the one that is worth their time and money.
There is no magic wand to solve this issue unfortunately, and if there was we’d all be doing it. Standard methods of promotion include social media (Twitter, Facebook, Instagram); engaging and connecting with literary magazines, book bloggers and reviewers and encouraging our authors to support and each other. We use a percentage of our profits to advertise our books and but ultimately it comes down to Return on Investment (ROI). It would be financial suicide to promote a book for £1000 and only make £50 in book sales as a result. This isn’t to say it’s not worth trying, all advertising is a risk, but authors and publishers must live within their means. This is why there are sadly so many despondent self-published authors who are essentially begging people to read their titles for free. Many publishers are also folding as their profits disappear. We have seen and heard horror stories of authors and publishers spending thousands on advertising, with next to no profit, and downward spirals of even more money being wasted as they try to recoup their losses. As a general rule, we allocate 20% of our net profits back into promotion – slow and steady wins the race!
We understand this is likely to be disappointing news to many new and established writers, but it would be pointless to say differently and mislead self-published authors. We would not want to establish a professional relationship with someone we had filled with false promises and expectations. The book industry is what it is; and for those who blame Amazon, it’s worthwhile to remember that Amazon (or similar print-on-demand companies) are also the reason they are able to exist and sell their books in the first place.