One of my old bosses is building his business online. Some of the ways he brings in an income is by way of affiliate programs. I know several other online entrepreneurs like John chow who are also making a little extra money this way. But I also know that most of these guys and gals trust in programs that they use personally or have a similar interest in.
For example, if you're a writer like I am, you might not want to consider using a weight loss affiliate to create a little extra money, since your readers are visiting your website or blog for writing or stories. However, if you have a fitness blog, this type of program would be perfect for it since many of your readers would be interested in weight loss and fitness.
Knowing who your readers are and sticking with affiliates that are similar to your website or blog's subject, gives you a better chance of becoming a successful online entrepreneur like my old boss and John Chow.