Logistics and Audience
A good place to start is remarketing. Focus on the warm traffic that’s already visited the site but hasn’t bought, because it is dramatically easier than trying to get cold traffic to convert. The dynamic ads make content a lot easier.
Make a conversion campaign optimized for purchase, and if it’s a new ad account, start by targeting interests. You can track which interests are working well and which ones aren’t. Take one interest per ad set. So, if you want to test three different interests against each other, then you would have three ad sets.
To keep things simple, start with the same two ads in each of those interest based ad sets. Then, keep the copy the same in both ads and just change the image in each of them, so that you’re limiting the number of variables. Square images show up across Facebook and Instagram really well and fits in pretty much all placements. Run those ads for five days and choose the winning ad.
A good rule of thumb here is 1 - 1.5X your average order value and run it for 5-7 days to see how it does. If you increase your spend, you can run it for a shorter amount of time.
Select images with pretty different concepts, not just a color change. This will really give you insight and learnings as to what works better.