The key message here is that you cannot start this process too early. One of the great advantages of being a published Author is that it sets you apart from the crowd. It makes you an Authority on your chosen subject. So announce yourself as an Author, and you will be asked to speak at events, and appear on Radio, even local TV. Prior to the publication of your book think about the raising expectation for the launch. Visit local independent book shops, create local interest. Have a chat with the local paper. Think about the launch, get the press along. Think hard about WHY you wrote the book in the first place.
This video might help you