Search engine optimization can help a lot in making your blog earn you some decent income. One way to use SEO is through keyword research. Now I'm not saying that you keep on stuffing your blog with keywords but most of the time there are lots of keywords/phrases that one blogger don't get to incorporate in their blog's content but are actually very relevant to the blog's topic.

Write useful information and use some of those keyword every now and then and continue promoting your blog through various traffic building means and you'll start earning from your blog gradually. This of course depends on how you monetize your blog. If it's AdSense, given the right niche blog, it will be easier. If you use text link selling, you have to establish your blog's traffic and pagerank first.