In the early days of e-commerce, users were limited to the few content management systems that were set up specifically for those purposes, like Zencart, Bigcommerce and Spree. Now, people starting out rarely use a content management system of their own, and instead use a hosted platform like Shopify or Square.
The best way to find the right hosted platform and to get off on a good foot is to simplify your offering as much as humanly possible in all the major aspects of selling: Have simple products that have a simple pricing and discount structure, simple shipping options, and are easy to fulfill.
However much you simplify, you will still likely need to install plugins, add-ons, extensions or whatever your particular platform calls the bolt-on services you'll pay additionally for.
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