im also a self taught artist, whose been doing art seriously for 10 years now?? i guess????? i think my biggest advice is... allow yourself to be influence by other artists. The biggest way i have improved is learning how weight is being held on characters (i should mention, i'm a character artist)
references are a HUGE help, especially for angles you aren't sure how to tackle yet. online art tutorials can be helpful, but they don't help you if you want to just improve upon your style. draw strange things, weird poses, even if they feel wrong just do it anyways! its one of the best ways to get a feel for your style; draw something you don't normally do!
you'll want to break out of your comfort zone in order to improve, you obviously don't have to do that consistently, but try and be flexible for when you do have motivation!
though, sadly, the best way to improve in your art is to learn the basics then go back. i said fuck that, which i get the vibe you're the same way so yeah. best advice; let yourself be influenced and have fun and you will find you've improved