Creativity works best.
Great question! Firstly, you want to get the visuals right. We recommend you replicate what worked best in your social channels.
Put yourself in the shoes of a potential customer: when you see something new from a brand you don't know much about, the visuals make a big difference. Then keep things friendly and exciting to get the viewer clicking.
Button text is also important, sometimes saying 'BUY NOW' can be a bit aggressive compared to injecting your personality and saying something more fun like 'CHECK IT OUT!'.
When all is said and done, you should experiment, try a few different things, and we'll tell you in your stats what worked best.
Here are some examples of some post checkout/email content we love: