The first “secret” is to visit the following KDP help page. This page tells you how to use different combinations of keywords to get your book listed in “special” categories. Once there, cick on a category from the list.
At CreateSpace, you can select one BISAC category and enter up to 5 keywords separated by commas in one of the publishing steps (same page as where you enter the description). At Kindle, you can select up to two categories and enter up to 7 keywords.
First, you should try searching for similar books on Amazon by keyword. As you start typing a keyword, common search results will pull up. This will help you see if customers ever search for the keywords that you’re trying. See which books similar to yours show up in the search results. Are the top searches all bestsellers, or have lesser known authors achieved visibility on these searches?
The most important thing about the keywords that you choose for your book is that they are a good fit for your book. That is, people searching for those books are very likely to be in your target audience. If not, the keyword is wasted. The second thing to consider is this: You want to balance popular keyword searches (i.e. ones that customers are likely to use frequently) with your chances of being visible in that search. Guess how many super-popular books show up if you simply search by “romance,” for example. You might be better off trying to find specific romance searches that are highly relevant for your book and which customers actually search for periodically.
Here is a handy keyword tip for CreateSpace: Don’t put spaces after your comma. The 25-character limit includes that space. So if you include a space after the comma, CreateSpace will reject an otherwise 25-character long keyword. (Obviously, you have to have spaces between separate words, just don’t put one after the comma that separates two keywords). Note that Kindle Direct Publishing (KDP) doesn’t impose this limit on characters.
Words in your title, subtitle, author name, and imprint are already searchable, as is the word “book.” So, for example, if your subtitle has the word “mystery” in it, you’re wasting a keyword if you choose “mystery book” as a keyword because it would already be searchable that way. Plurals may make a slight difference in the order of search results, but you shouldn’t waste a keyword to change something like “soldier” to “soldiers,” for example (if you have one or the other, your book will show up in both searches, though not necessarily in the same place).
As you find books similar to yours—especially books where the author wasn’t well-known, but which are selling well—see which categories they are listed in. You want to choose the most relevant category for your book.
Although you can only choose one BISAC category at CreateSpace, you can actually get your book listed in two relevant categories at Amazon. After your book is published, simply contact member support and politely as CreateSpace if they could please add your book to one more category. First go to Amazon to find the browse path—something like Books > Romance > Contemporary.
You have to make a separate request for Amazon US and Amazon UK. Note that the category choices are different on both sites, so you have to find the category that you want on each site before making the request.
You can’t add your book to a second category in children’s or teen unless your BISAC category is in juvenile. If you want one category in children’s or teen and one category different from this, first choose your BISAC category within juvenile and then request to add the other category on Amazon.
When your book first goes live, it may be way down the list (several pages, perhaps) in search results. Through successful marketing, if your book gets searched more and sells after being searched, this will help to improve the book’s position in the ordering of search results. You can’t expect a new book to pass bestsellers in the results, can you? It takes time for Amazon’s program to establish relevance.
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)