There is no magic formula for creating the perfect email marketing campaign. A lot of it is going to come down to the knowledge you gain from each campaign you send.
Split testing is one of the most effective ways of figuring out what works and what doesn’t work for your audience. Also known as A/B testing, a split test involves sending two different versions of your email message to random halves of your email list. You can then see how customers respond to different copy, subject lines, and design.
No change is too small to test. Ecommerce masters such as Amazon are constantly testing minor tweaks to the colors, messaging, size of buttons, and other elements of their marketing. You should do the same on a regular basis, and you should use an email software that makes it possible. Only then can you gain the insights to improve your future marketing efforts.