No matter what your specific goal is in marketing your art, the absolute key to success is consistent, focused effort. It takes time and hard work to create your brand and awareness of it. “Overnight successes” rarely are.
Marketing art is a bit different from marketing other products and services, but not as much as you would think. All the basics still apply. You need to create awareness of your brand, you need to deliver a great product and terrific customer service, and you need to be aware of the market conditions for the product you are offering so that you price appropriately.
As an artist, your brand is you.