Every Recognized Expert should have an Expert Proof Product (EPP), or better yet – several that make up their Expert Proof Materials (EPM). An EPP could be a book, or a DVD or an audio CD, almost anything that demonstrates that the person is an expert in a particular subject, has definite ideas and opinions, and can reasonably be considered an expert on their subject.
In creating a non-fiction book (a novel could be considered EPP if the person is establishing their credibility as a fiction writer, or perhaps as a creative writing teacher), you don’t have to start from scratch. Putting together a series of articles or blog posts into a narrative that explains or explores the Expert’s niche is perfectly acceptable. Adding in some charts, perhaps even a transcript of an interview or two is also a possibility.