Hello! I am about to make an advertising campaign in Facebook for attracting new subscribers for my mailing list. I plan to spend about 50-60$ for it (it is very small, local language market). I want to make the most professional and smart way and that is why I wan to A/B test something.
So my question is: which element (variable) would be most optimal to put to a A/B test in that case?
Put another way... what would be most worthy to test?