Affiliate programs used to be a path to riches. Back in 2005, if you had a high traffic website, you could place ads on your website that referred visitors to other sites, in exchange for a commission on anything that was purchased. One of our clients made a fortune doing exactly that, with a website that sold nothing itself, only referring others to purchase through Commission Junction (since renamed to CJ Affiliates), and by selling banner ads and text listings on the pages of her website.
While Commission Junction was rebranded and is still functioning, we do not currently have any clients using it, so we offer no advice concerning it. Ten years ago it was worth pursuing. Nowadays? Unknown.
Here's a good recent blog post on the current Commission Junction affiliate program, from Priscilla Tan of Smart Blogger. They also have articles on that site about some of the other affiliate programs; reading those may help you make up your own mind about them.
Keep in mind that in recent years Google has cracked down on affiliate websites, making it very difficult for affiliate sites to rank high enough in Google's Search Results Pages to get any traffic. Such websites are competition for Google's AdWords program, and Google has been utterly ruthless (in my humble opinion) about putting their competition out of business.
Bluntly, if the purpose of a website is to make money by referring all their visitors to other websites, Google will typically bury that website way down in their search results, where it will never get clicked. An example of this would be one of the innumerable "Amway Distributor" sites, which pulls all its content from and sends all its traffic over to Amway.com. So if that is your purpose, to build a website that gets high rankings and then refer all your visitors elsewhere in order to make money from Commission Junction or ClickBank—well, we're not seeing that business model work (at all!) and we would actively dissuade you from going in that direction.
However, if you have a website that has killer content and which a lot of people visit, and you're not selling anything of your own on it, then by all means set up Google AdSense or another affiliate program and make yourself some income from the hard work that went into obtaining all those visitors.
Here in 2023 the only affiliate programs we would recommend are Amazon Associates (where you link to specific products for sale on Amazon, and Amazon sends you a referral commission when people buy after clicking that link) or Google's AdSense program, where you make money from Google when someone clicks an ad (coming from Google Adsense) displayed on your website.
Here's a very detailed analysis of how affiliate websites ranked at Google in 2020. (Summary: It really depends on what you are selling and what kind of niche it is, and whether Amazon is also selling that product.) Niche websites and hyperniche websites seem to do best at ranking highly on Google for affiliate products... after Amazon, of course.
The rise of popular Youtube channels, and the monetization of those (which I won't get into on this page) makes it worthwhile to look into how to make money with this. Various Youtube celebrities have made money and then been slapped down by "deplatforming" them. It's a risky business model if you are doing anything which is not politically correct. Here's a "How Things Work" article from Youtube on "How to make money on YouTube."
Best of luck to you in this - if you have any questions feel free to ask me.