If there are good traffic in your site you can earn well by google adsense. If you get any good offer you can sell it.
Publish informative content in blog on regular basis. Submit your blog in Blog submission sites and do bookmaring and directory on regular basis. Promote your blog in social media site like facebook, twitter, linkedin, pinterest etc. As much traffic your blog will that much money you can earn by running adsense or paid ads.
Making money online is now readily accessible to anyone who wishes to earn a living. Writing blogs is just one of the many ways on how to make this into a reality. The easiest way to do this is to create and post your blog on free services such as Wordpress or Blogger.
There are even ebooks that can help you grow. Try finding a SEO or Blogger ebook, and you will find all you need to know.