The joy of building backlinks…
Building backlinks is fundamental to your off page SEO strategy.  Building them is a pain.  Here are the steps:

Find sites related to your niche that allow comments with HTML
Check to make sure the site provides a DO FOLLOW link
Read the blog post or forum thread and make a comment relating to [...]

A lot of websites are only marginally profitable when only 1 form of monetization is used. Google AdSense is a very easy way to add another way to monetize your site. With any luck you go from marginally profitable to comfortably profitable with about 10 minutes of work.