CPA (Cost per Action) marketing has a big potential. First of all, to earn the commission, you don’t necessarily have to sell anything, a simple signup with an e-mail can pay you. Secondly, there’s no such thing as refunds in CPA marketing. Once you refer a person to enter their personal information and get a commission for that, that money is yours.
To better understand the science behind CPA networks and CPA marketing, Chris Cobb has created CPA Arbitrage. It introduces the student to the world of CPA, teaches the methods to get traffic specifically for the CPA offers and how to generate those leads for which you get paid for.