A friend of mine once won Best of Show at a typical "art in the park" competition for one of her many abstract watercolors. It was a huge, beautiful thing, full of painterly tricks and technical expertise she'd learned or devised herself over the years, resulting in an eye-catching work that seemed to be appreciated by even those in the crowd whom one might not expect to like abstraction. Her award rated her an on-camera TV interview which quickly turned into an incoherent babble of nothingness when she was questioned about her work, it's inspiration, and abstract art in general. It was embarrassing to watch. It was obvious that she knew only about the technical aspects of painting, while everything else was intuitive, and she was either unable to unwilling to discuss this aspect her work in any way whatsoever. I suspect she was mostly interested in merely playing with pretty colors and interesting effects rather than drawing from within herself in any deeply creative sense.
Thus, as I see it, four things make up a successful artist. (1.) DOING art. That means knowing how to paint and then doing at least a reasonable amount of work to prove it. (2.) KNOWING art. The artist must know where he or she is coming from and have at least some idea of where they are going. It means being aware of past art and cognizant of present art. (3.) BEING something more than JUST an artist. Otherwise, that which the artist creates will ring as hollow as the Best of Show abstraction my friend did. What the artist IS makes up the substance of what KNOWING art and DOING art is all about. And finally, (4.) the successful artist must be willing to "stand naked" before everyone seeing his art, saying this is who and what I am. He or she must be ready, willing, and able to take everything the "public" has to throw at them (both positive and negative), and if need be, throw some of it back. Sales? Yes, money is nice. But it comes as an adjunct to these other elements, as does marketing savvy, business acumen, and salesmanship. All these things are important, but, the successful artist, in the final analysis, can pay someone else to do all of them if they're willing to foot the bill. The BIG FOUR, however, are absolutely essential.