Many artists nowadays use social media platforms such as Twitter, Tumblr, and Instagram to sell their art. Start by creating an account, using your professional name, and ensure the profile is filled out completely to add legitimacy. Post consistently (at least once a day) to gain traffic and build up a larger following. Also try to use relevant keywords so that your work can be easily found by potential clients.
Don't be discouraged if it's slow to start, as your follower count rises, so will your sales.
Ever since Etsy was launched (in 2005), it has been a favorite spot of designers, crafters, artists, and painters for showcasing and selling their artwork to online customers. Etsy’s popularity has a benefit as well as a drawback. The popularity enables artists to access a large marketplace where there are plenty of buyers looking for decent artwork. However, Etsy's popularity makes it challenging for artists trying to make a living off Etsy because they face stiff competition.