Submitting to literary journals has always helped me because it keeps me on my toes. Even if I have to submit to the same journal over and over again before a piece is accepted! It gives me something to work towards.
I’ve also found that volunteering on the staff of literary journals has been immensely helpful as well because it gives me so many inspiring connections to other writers. For example, I’ve been a guest editor for a magazine where I edited a special issue for them, and I was also a contributing editor at one point for another magazine every week. Good places to start if you’re interested in that would be The Adroit Journal, cahoodaloodaling, Spry Literary, or Up the Staircase Quarterly.
Submitting to the annual Scholastic Art and Writing Awards can be useful as well because of how hard it pushes you to think creatively.
Overall though, remember that a writer’s success is not defined by the number of publications they get! Good luck :)