Implement ongoing and active AB testing process!!
It is easy. It usually don’t cost any money. And it can delivery quick and frequent improvement that will help your bottom line.
Start with subject line AB testing, if you’re not doing it already. Then upgrade to AB testing key portions of the message copy, call-to-action copy, and even copy format (bullet list vs paragraph, etc). Finally, if resources allow, AB test design (hero photo type, size, button style, color, layout style, CTA placement, etc).
Just make sure to AB test one variable at a time, and watch for statistical significance in your tests. Easy. Fast. Beneficial results.