I used to do CPA marketing, but it is just terrible, it sounds simple for beginners that just fill out a form, but trust me you do not wanna try this, it is not worth it, what it is worth is some affiliate program with pay per lead like Skillshare or Sendinblue, they pay like 5 or 7 dollars about each free account that is made through the special link of yours. Honestly, I would say just join normal affiliate programs, they are hard at the beginning and do not work great in the short term but for the long term, they are really great