ClickBank allows you to join for free, and the approval process is virtually automatic, so it’s a great choice for people entering the affiliated game for the first time. ClickBank has a ton of information, including FAQs, walk-throughs, and videos available, so the barrier to entry is quite low. There’s also a (paid) program called ClickBank University with courses and assistance from experienced marketers.
Some commentators originally suggested that affiliate links work best in the context of the information contained within the website itself. For instance, if a website contains information pertaining to publishing a website, an affiliate link leading to a merchant's internet service provider (ISP) within that website's content would be appropriate. If a website contains information pertaining to sports, an affiliate link leading to a sporting goods website may work well within the context of the articles and information about sports. The goal, in this case, is to publish quality information on the website and provide context-oriented links to related merchant's websites.