How could CPA not be easy!
It stands to reason that even if the people aren't interested in the offer since ALL they have to do is put their email in they'll do it anyways! Right?
Wrong! The real people who success and profit with CPA are creative and know how to identify with their targets, be it by text ad, or landing page or the content.
The only people who really profit using all the tools you think you have access to are the ones that automate things AFTER they have it right.
Just think about the question for one minute... if it really was EASY then you wouldn't have asked the question in the first place, you would be making money off of CPA already.