We respond well to small delighters.
Can you create some small and unexpected pleasurable things to delight your visitors? It can be a small game, a video or maybe you can trigger the gatherer in your visitors and let the collect points or badges or other stuff on your website. Don't go overboard though, it's all about the small things. You don't want to distract people from actually buying stuff on your website. An example of a fun delighter in the Mailchimp interface:
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.