Instead of using just one blog, use several. Some of the best bloggers make the most money by maintaining several blogs at one time. If you become really popular, you can even get people to help you with the blogging posts.
Multiple blogs means that you blogs are targeted to specific audience. You will have more repeat visitors this way. This in turns means more chances that readers will click ads that they find interesting.
Multiple blogs also mean that you can SEO your posts so that they will show up better on search engines. Of course, the higher they show up on search engines, the more traffic you will have to your blogs. Blogs are a great way to feed money into your pocket.