As a self-publishing author, you can use a blog to build content for your book, gain the attention of your target audience and promote your book (before and after it is published).
There are several blogging sites you can use. Here are two that I recommend and they are FREE:
Be sure to let viewers know how to subscribe to your blog. WordPress has a widget you can add to your sidebar (look to the right) for readers to enter their email address and have the posts delivered directly to their inbox. This keeps readers updated whenever you post new content.