Keep your marketing profitable and targeted. In other words be cost-effective in the way you spend. Promotions can be hugely expensive. Rather than re-inventing the wheel, ask others what they found to be lucrative. Do your research. If you blow a bunch of money and get poor results in either free downloads or sales, rethink that cost.
Also take into effect that not every book is on the same level as another. Some have more reviews, there are price differences, many of the authors have a huge backlist and a fan base already in place, others are novellas, or maybe a series book. Covers can be distinctive and make sales. There are so many differences that can drive a book. Start paying attention to help you understand.
You can’t write a book everyone will love, therefore maximize your promotion toward those most likely to become your audience. Isolate those people who would be interested in the content of the book. For instance, I know my Vicarage Bench Series and the Angels with Attitudes wouldn’t be of any interest whatsoever to the majority of male readers. On the other hand, I happen to know that there are a few men who’ve enjoyed the grittier, romantic suspense Vegas Series. So, it goes without saying that I wouldn’t aim my marketing to the same crowd for all my books.
Identify other work that is comparable to yours and look up those books’ main customers. Explore the connections and what worked to attract them. Then appeal to those books’ readers. On Goodreads ads they ask you to give them a list of authors who write books similar to yours. They know it’s important for you to locate those booklovers.
Pinpoint what is special about your book. For instance…when I wrote my time-travel series (Vicarage Bench) I mixed it up a little by deciding that rather than just sending my protagonist back in time, I’d put her spirit into the body of another person, usually one of the opposite sex. Legitimately, I can call it a time-travel romance; the twist just gives it more layers of conflict.
Determine some demographics. What age would be most likely to enjoy your book? As mentioned above, is it likely to interest both men and women? Do you really think that an erotica lover will totally enjoy your sweet inspirational love story? Or teenagers who love Sci-Fi would be into a contemporary romance? Aim your books and budget towards the people most likely to write you a great review.