If you plan on starting your own online store just remember that HTTPS is required to collect customer data, so be sure to purchase your SSL certificate before launching your website (otherwise you’ll have to redirect HTTP to HTTPS and it can become complicated). You’ll also want to consider creating pages for your Site Use & Privacy Terms as well a Refund Policy.

This is of course in addition to filing paperwork required in your locale (country, state, province, etc) to sell products and/or services.