It’s 2007 and Most E-Commerce Sites Suck Like It’s 1999 →
https://marco.org/2007/06/01/its-2007-and-most-e-commerce-sites-suck-like-its-1999
(thanks AZspot) I’d take it a step further and say, “Just do everything the way Amazon does it, except their search, which sucks.” Buying things from Amazon is remarkably pleasant compared to almost every other web shop.