"As the revenues from online sales continued to grow significantly researchers identified different types of online shoppers with four categories and named them "convenience shoppers, variety seekers, balanced buyers, and store-oriented shoppers". They focused on shopping motivations and found that the variety of products available and the perceived convenience of the buying online experience were significant motivating factors." ~Wikipedia
You have several options for your E-commerce platform, from simple PayPal Buy Now buttons, to integrated shopping carts like Ecwid, to stores like Shopify. The E-commerce system integrated depends on the amount of products and/or services you have, and your budget. Monthly costs for PayPal are none, Ecwid starts at $15 per month, and Shopify averages around $50 per month with several useful apps installed.
The MousePads.Cool store is Shopify, Riley Weston's is Ecwid as are the rest of the store links below.
An area to consider in building your new store is the option to integrate "print on demand" where you take the order in your store including the funds, but a third party prints/creates the product, ships it to the customer, and collects a smaller fee from you for that service. It means you have no inventory, no upfront cost, and no shipping & fulfillment requirements. This is great for items like t-shirts, clothing, hats, mugs, pillows, posters and wall art, etc. You simply create the text and/or graphic, upload it through your store, choose which product or products to apply it to, set a price, add a description, and your product is then live for sale.
You also have many apps that may be installed inside your store both initially, as well as when you grow your business. One great app for your store is an automated product review system. Nothing sells you and your brand better than reviews and testimonials. Here's a link to one that automatically sends out a product review request, after a specific amount of days after their order has been received, and it allows for photos, text, and videos. It evens sends out a reminder after a while. It is 100% automated.
"Making a profitable e-commerce store is hard work. I love the fact that Shopify clients help each other in our forums. I love the fact that everyone feels like we are in this together and that we all will succeed together." ~Scott Lake,co-Founder, Shopify