Love eCommerce and I've been at it since it started and love it (well its just retail but with real time information and results!) Sounds like you are new to it all and perhaps to your own business?

I knew there where some great blogs on your topic and recalled Shopify had a good one so my quick google surfaced this, it likely answers all your basic questions.
ecommerce business blueprint
https://www.shopify.com/blog/ecommerce-business-blueprint

If this is too basics and or you want deeper success insights, Happy to take a call as Ive built/led/grown ecom businesses that do $100M to $billions, as well as technology companies that power eCommerce (Magento, Temando, Wpromote...)

Enjoy your jouney!