Every year the price for advertising online goes up. Its just how it works. That means every year you have to get better at converting the traffic you buy into conversions.
The only way to narrow down the best advertising, that produces consistent conversions is to split test.
Example would be when buying mobile advertising. You can split test different smartphone devices. Send traffic to “Samsung” only phones see what you get. Then split test it with “Nokia” phones.
With regular desktop traffic you can split test different banners and landing pages.
I don’t spend to much time on changing colors or small text changes. On my landing pages I just create 3 different versions, with 3 different headlines and split test them all.
Once I find the banners and landing pages that convert, then I just ramp up my advertising.
So split testing is a must if you want to have long lasting success online.