Extensive user research with people shopping online identified 5 main types of behavior: product-focused, browsing, researchers, bargain-hunters, and one-time shoppers. Each user type benefits from different UX elements.
Conversions measure whether users take a desired action on your website, so they are a great metric for tracking design improvements (or lack of same). But non-UX factors can impact conversion rates, so beware.
Useful search suggestions lead to relevant results and are visually distinct from the query text. (This is about how to design the search feature on your own website, whether it's an ecommerce site or not.)
Optimize the checkout experience on mobile ecommerce channels by taking into account the strengths and limitations of mobile devices. Aim to minimize the number of steps and typing, and take advantage of capabilities such as geolocation and the camera.