So many of us authors struggle with platform. Here is some good advice that I found:

In the book, "Get Known Before the Book Deal," Christina Katz says, "The word platform simply describes all the ways you are visible and appealing to your future, potential, or actual readership. Platform development is important not only for authors; it's also crucial for aspiring and soon-to-be authors. Your platform includes your Web presence, any public speaking you do, the classes you teach, the media contacts you've established, the articles you've published, and any other means you currently have for making your name and your future books known to a viable readership. If others already recognize your expertise on a given topic or for a specific audience or both, then that is your platform. Long story short: Your platform communicates your expertise to others, so you don't have to."