Yes, commissions are very difficult to get. I remember in the first few years I also sold art for like ten or fifty dA points. I also has months and months with no one biting for commissions.
Now, I've been doing them for nine years and only last year (I've taken a break for a year cause comics) for a year had I started to make in the hundreds per month. All from DeviantArt clients.
Now, what I'd discovered is that clients often don't know what they want in a commission. They rely a lot on the artist for creative freedom. Only a small slice of clients I've worked with always knew what they wanted to see. This is unreliable when you're not a well established artist as everyone who has posted so far knows.
In my research around deviantart's commission and adoptable markets ...mostly just lots and lots of looking at successful ones and how they're different. There seemed to be two successful veins. Those that had a set style, super technically good art, and have just been grinding away at the commissions game for many years to establish themselves is one. I knew I would get bored making just pretty portraits so I looked for a different way.
That's when I came upon Your-Character-Here (YCH) commissions. These seemed to be promising.
For those not familiar, YCH commissions have a pre-drawn base of blank figures in some interesting pose that the creator can then auction or buy outright. It's only when I started making those did I even start to see a steady stream of people wanting my work. Because now people didn't have to think of their own pose, they could point at the one I made and be like: I want this one.
Here's the important bit: It was still slow going, but it was more than before so I knew I was going in the right direction.
After that, I got to thinking that I always want some kind of story illustrated in my art. Getting really neat portraits of characters is cool but anyone can do that. And if anyone can do it that means there is a LOT of competition.
That's when I started making YCH comic pages. Single scenes with a bit of dialogue. I decided that what I'm selling isn't the art or my style. I'm selling the client a story; a chance to point to the YCH and say I can see my OCs in this!
They're not easy to make and it does take a lot of experimenting to make something even off of Pinterest dialogue prompts for example.
But since making this and letting multiple clients order the same scene, I've made hundreds of hundreds of completed commissions.
I've made over 150 unique YCHs now and ALL of my YCHs are free to use as Bases, References, Inspiration to anyone for anything. This includes anyone wanting to use them to offer commissions. And I'm more than happy to confirm that as needed on dA.
It's taken me nine years of freelancing to figure this all out.
https://www.deviantart.com/seraphicmayin/gallery/69016239/old-ychs
These are all the YCHs and in September I plan to start creating more cause my comic Swaha is almost complete.
If they help, please feel free to use them as resources.