I have the impression from the comments I read on websites for writers that many self-published authors do not fully appreciate a basic marketing law: Consumers must first be aware a product exists before they can consider buying it. This is why we have press releases, reviews, advertising, interviews—anything to get the word out.
And you want to get the word out to people who buy and read books. Independent bookstores have always been a wonderful source of getting the word out. There was a time (perhaps mythical, perhaps real) when the bookstore owner and clerks knew their customers' interests and preferences well enough to suggest new titles. (Amazon is trying to accomplish the same thing with its "Customers who bought this item also bought" lists.)
Libraries are also filled with people who read books—and, according to Library Journal—50 percent of the people who start an e-book they've downloaded from their library actually buy the book. I have been giving my book to libraries where (a) I have a relationship and (b) the library is willing to put the book into the circulating collection, which is not always. However, in some cases, the librarian has actually put the book on display where, as in the display illustrated here, it was immediately checked out.
In the best of all possible worlds, the patron read Death in a Family Business and liked it enough to recommend it to friends and acquaintances and, like ripples in a pond, the friends told friends and so the word got out.