like a painter for example.

sell your stuff for lots of money.

if there was a scheme in getting rich being a freelance artist, then everyone would be an artist.
artists who have made a considerable amount from their work have paved a way in a particular genre, or they have made a statement through their work that revolutionizes.
Though, in actuality, few artists in categories mentioned above see the fortunes they make, because their art & ideas don't become popular until after their demise.

if you are asking the question out of consideration of a personal goal, then definitely don't pursue it. you should do something out of passion and joy, not to get money. and when money is your passion, you'll never make anything of yourself as an artist.

show, show, show, and show some more... until people want to buy your art. and then you show even more so that people can come and buy it. many painters work with art dealers who help get the work into well known shows and to people who are looking to buy art. Its rare that you get rich doing this, but you can make a living if you're lucky. Most of us don't.

Some fine artists make a lot of money, but most don't. Go and study under the best artists you can find. Become the best at what you do , that means study and practice a lot. Show your work to the best galleries and collectors.