There are tons of ways to monetize a blog. Here are a few of them:

• Google Adsense: Depending on the niche or topic your blog dwells on, Google places ads automatically. When people click on these ads, you get a share of the ad revenue.
• Text-link-ads and other link brokers: Place your website or blog for review. When accepted, these brokers will find relevant merchants whose website links can be displayed on your blog for a fixed monthly income.
• Affiliate Marketing: By placing relevant text links, banners, sending emails, and adding content on your blog to promote products and services others' create, you make money by referring your readers to these brands.
• Direct media selling: If your blog has commercial value -- that is, if it gets enough traffic -- you can sell ad space on your blog directly to local or international clients who'd pay you for the visibility and relevance.