I hear this question a lot from artists, art lovers, and collectors. The truth is that there is no clear answer. Each artist has their own idea of what success is.
For some it is making lots of money off of their art. Others will say simply being able to make their art and have exhibits. More will say being able to live off what they make on their art, and yet others will say simply working on their art, while for even others it is about having museum shows, their works in collections and doing public works for the world to see.
Some artists ideas of success will also change over time. In the beginning of their carrier artists who are still trying to find themselves might just want to be able to do their art.
By the time you enter the emerging stage artists might simply want to make their work and have exhibits. As you continue to emerge as an artist you may hope to sell enough work to live off of, while some look forward to the day that they can sell their work for lots and lots of money.
The truth is that only about 1% of 1% of artists make enough money to live off of, and only 1% of that make enough money to be comfortable, and still only 1% of that make a lot of money.
These days most artists have a second jobs, not because they are not sure in the work that they are doing, or not because they are not creating great art, but for reasons like they need to pay rent, insurance and eat, and for a small number of them it is the fear of failure. Those that live off their work will tell you that it is a risk. You are putting everything you have into your art, with the hope of not only making your money back but also making enough to pay rent, eat, insurance and transportation.
When I talk to people about how I got into art I tell the story of how when I was younger and talked about being an artist, my family told me that I could end up like the artist on the street who spend their days drawing people for $5 a session. While to many that would seem like bad thing to me it sounded exciting. When I retired from the military and put my life into doing my art, I thought about would I be that kind of artist or would I really be able to live off the work that I loved doing. I leaped, taking the risk, and while it has not always been smooth, I have been able to live modestly off of my work.
The hardest part is to stick with it. If you start to doubt yourself or fear being able to make it, it will only get harder. I have seen many artists walk away because they have not reached the level of success they wanted in a certain amount of time. But this is not something that you can put a time line on. Part of the key to all this is keeping your work fresh (something I will go into in my next tip).