You may have a niche site, and it’s fine to have one, but even if you do, be sure to use keywords your users understand. If your audience doesn’t know the vocabulary, isn’t searching for any of your terms, or doesn’t understand the vocabulary in your ad, your ad won’t show up and won’t succeed.
Example: Our family business includes a website where self-publishing authors can upload their book excerpts, which will then be featured on barnesandnoble.com, as well as a number of other websites. This helps the author promote their book. However, what we found is that self-publishing authors didn’t understand the terminology we were using. Our slogan was, “Our excerpts promote browsing and help sell your book, whether e-book or print format.” But the authors didn’t know what that meant. As a result, although we would get clicks from the keyword “how to promote your book,” we did not get a lot of conversions. Users couldn’t understand what we were asking for.
Moral of the Story: Only advertise on keywords (and using ad copy) that your audience is already using and understands. If your site or product is completely new, think about what keywords your audience (people with the problem) would already be searching for. Those are the words to be on. Because if you’re a reverse mortgage website and you are only advertising on “hecm,” (the industry term for a reverse mortgage loan), you will not reach your audience.