I've been a freelance illustrator full time for a decade, and part time for another decade before that as I taught myself the digital programs I needed to make my images more realistic. My income stemming almost entirely from commission work ever since I entered the digital world.
Because I was so busy with commissions, I rarely ever had time to create my own artwork.
Before that (during the 1980's-1990's) I painted in Tempera Paint and Prismacolor Pencil and sold signed numbered prints of my paintings all over the US at over 50 Gaming, RPG, sci-fi, fantasy and comic convention art shows a year - and gained quite a following. But there was more praise than money in that field, so I decided to expand.
Once digital came around, I knew the only way I could learn to work digitally was to get paid for it. When Windows 98 came out someone gave me their Windows 95 computer. I hit the library and taught myself HTML, got on freeservers.com and built myself a website. I used that to show my art online and shared my link with websites that displayed fantasy art from various artists.
Eventually, I dropped the gaming conventions and the art style altogether as I learned image editing programs from Youtube videos til I found one that worked for me. I looked for businesses who needed art to make their living and found a few - especially a small wallpaper business in California who wanted to commission me to do scenes and border wallpaper that he would then print and sell on his website (he's since retired).
I was creating scenes digitally that were as big as 8ft high by 12ft wide. Standing in front of one put you right into that scene.
I learned a LOT struggling through trying to figure out how to digitally create the art he wanted in the quality he needed to sell the designs. I learned to use layers to make it easier to change my image, and because the client was very specific about what he wanted, I learned to follow directions .
I made very little money, sometimes less than minimum wage, but learned so much that I eventually branched into 3D modeling to make my workflow even more versatile. Now, after 2 decades of doing only commissions in this digital style, I've reached a point where I feel I can start creating my own art again, in the quality I'd always strived to produce, and move from the "illustration" world, back into the "art" world.
If I can create enough new art over the next several months, I may start a Patreon and offer things like reproduction rights, 3D models, and tutorial JPGs or videos of my process.