Self Advertisement. You need to create a visually appealing Ad that is also readable as a smaller image so that when people glance it both catches their eye and also shows that your commissions are open. Also doubling by Making a journal anytime you post your ad to make sure journal readers can see it, too. You should never use fancy text fonts because not only can they be hard to read for native language speakers, but can be impossible to read for people who's first language is not english. No cursive, curly, or fancy fonts. The name of the game is spoon feeding people's eyeballs to make sure it is easy for them.

Any time that I want to take on commissions, I upload my Commission Ad https://sta.sh/0ispt28jkqv
Be sure to have a limit for how many you take. It helps you to not overwork yourself and accidentally get burnout. For someone new to commissions I suggest only taking on one or two at a time and wait until you finish those ones before opening commissions again. And again, it is important to self advertise yourself whenever you feel up for commissions. posting a com ad and letting it sit will only work the very time you have posted it. Your ad will be washed down the newest stream, and harder to find as time goes on if you never advertise yourself again.

I also suggest to have an area where you commission info is always listed, that way when you are closed, people can still find your prices and save up. I would have this linked on your profiles, and always have it linked in the art you upload as well whether you are open or not just for this reason.