Decide whether you're only selling original artwork or if you're also selling prints. Especially during the pandemic a lot of artists that never sold prints are rethinking their stance -- archival Giclee art prints can be an effective way to expand your audience base and your brand and create an additional revenue stream.
Post frequently to your social media and follow art enthusiasts - a short cut here would be to see who's following other artists and follow those people. Instagram and Facebook are the best platforms for fine art.
Select an online store you'd like to sell and promote your original art and prints. They take a large cut of your profits, but save you the legwork it takes to run and operate your own store. Do the math for yourself and choose the best option for you.
Popular Platform to Sell Original Art and On-Demand Prints:
ArtPal
Fine Art America
If you'd like to be in charge of your own quality control and a chance to hand-sign your art prints before they're shipped to the customer, consider selling on Amazon, Etsy, or on your own website. In which case you'll need to select a local digital printing company so you can sell your prints on-demand.
An on-demand printing option means you'd have the prints made only when the order was placed or choose to place smaller quantity orders to avoid buying more than you can sell and having them take up space in your home or office.
Amazon
Shopify
Etsy
https://mymodernmet.com/how-to-sell-art-online/ This article, "18 Ways for Artists to Sell Their Creative Work Online" does a great job at going through each option and explaining how it works to help you choose the best platform(s) for you.
If you've found a way to sell hundreds or thousands of prints quickly or all at once, you can use a local off-set printer to produce your prints. Off-set printing allows you to produce a large quantity of art prints very quickly and affordably, so this could be a good option if the prints will only be on display for a few years. Keep in mind that off-set printing does not produce archival Giclee prints like digital printing does, which are meant to last 100 years.
If you're also selling directly from your website, I'd suggest setting up a store with Shopify to streamline the process. Shopify offers special shipping rates for it’s customers. It's very easy for customers to select a shipping method, get a shipping cost, and complete the purchase.
Shopify let's the owner print the label and pay the postage within the site and ship from home. It also lets the owner display full shipping costs and keep the discount for themselves or they can pass it on to the customer.
Select a local digital printing company that can print Giclee prints and put them in an appropriate container with a label indicating what's inside for your convenience. All you would do then is just leave a note for the mail person to pick up the packages whenever they drop off the mail for the day.
If you need an extra hand, here are services where you can hire personal assistants for administrative work:
upwork.com
thumbtack.com