There are no limitations on what your blog can be about. Any topic that interests you is fair game. And odds are, there already is an entire community of people who share your interests and will look forward to your next posting. Once you begin writing your blog regularly, it’s easy to get dozens, or even hundreds, of regular readers who will frequently leave comments and engage in an exchange of information and knowledge with you.
Introduction: Blog Profits
Creating Your First WordPress Blog
Writing Your Blog: A Primer
Monetizing Your Blog
Secrets of Successful Blogging