In previous posts I've mentioned marketing yourself by building a "platform". Your platform is basically the things you do to publicize yourself, to get your message out there. Obviously, we can't expect to just write a book or article and expect publishers to come knocking at our door or snatch up the work we send them and go to press with it. Publishers want to know why we should be considered a voice of authority on the subject.
As mentioned in the article "Building a Writing Career" by Sean Murray (excerpted from The Craft & Business of Writing from the Editors of Writer's Digest Books), "Teaching or giving talks on your subject can be an invaluable way of broadening the platform for your writing career, sharpening your own craft, and building an audience." A great place to start is with community organizations, rotary clubs, churches, recreation centers and local media. If you've already had an article or book published, even better. As Murray points out, this makes you an "instant expert."