Increase the (perceived) scarcity of something and it's value will rise.
Can you make your products look more scarce? People don't like missing a good deal or product and you can give them an extra push by making a product look scarce. Prevent people from holding of any longer from buying from you. For example, you could show a discount-countdown-timer or a 'almost out of stock' notification on your products.
Recently I've seen some (often absolute) statements going around, generally in the line of "open source commerce platforms are a terrible idea". Now of course different solutions always have different pros and cons.
A hierarchy of evidence (or levels of evidence) is a heuristic used to rank the relative strength of results obtained from scientific research. I've created a version of this chart/pyramid applied to CRO which you can see below. It contains the options we have as optimizers and tools and methods we often use to gather data.