eCommerce is the mail order business ported to the web.
The added functionality that the web has does not always lead to increased selling power. It can reach a broad audience, and simple tools drop startup costs to next to nothing, but the fundamentals of how the business works are very well established.
The catalog and mail order business is centuries old. There are established conventions that don’t make the transition to the web perfectly, but more of them do than people tend to realize. Other similar sources of inspiration for improving your sales include television product sales programs like long infomercials and QVC.
Don’t scoff: those methods are tested for response rates and conversions.