Commission Junction — This site serves as a clearinghouse for thousands of companies and small businesses looking to get into the affiliate business. It offers myriad affiliate programs, but you must apply separately to each one. Payout rates vary wildly, up to 50 percent, and some commissions are based on leads or clicks vs. sales. Frustratingly, Commission Junction deducts $10 from your accrued earnings for every month in which you don’t actively earn commissions; if you let your account lapse, your income could get wiped out.
Research individual companies in your desired niche: If possible, it’s always better to become an affiliate directly with a company (if they have an internal affiliate program), as no one else will be dipping into your commission rate. This is the preferred route for most of the prominent affiliate marketers, including Pat Flynn. Unfortunately, it’s also the most work, as you’ll have to do the research yourself to see who offers programs (they’re usually listed in the website footer).