well... primarily, id say keep working on your art. it would reeeeeeally help you to study anatomy and gesture. id also throw in studying colour; nice colours can, imo, make up where art lacks. like, the main thing is anatomy. its super hard to get down, i admit, and im pretty sure everyone at every stage is stuck on some kinda anatomy hurdle, but just focusing on it a little bit more would improve your work. focus on it a lot more, id say.
you say on your profile youre using pen and paper, so id recommend getting better fine liners OR working on your line smoothness. i mean, either way make your lines smoother but idk if the problem is your pens or just where youre at rn. your lines are wiggly, rough, and dont vary in weight - so practice just making lines, smooth lines and varied lines and straight lines. the problem might not be helped by your scanning process, ik when i used to scan images and up the contrast til i could get rid of the white the wiggly roughness was really accentuated.
personally, id recommend you get a tablet. HUION are fairly affordable, you could save up. it means you can do a whole lot more with your software, especially when it comes to shading. right now your colour is all block fills and it looks pretty dull, if you had a tablet you could make it more interesting. although, before doing that, id change your colours to work better with eachother. find some colour theory tutorials on tumblr n dA, mayb find some books on it.
ill be honest, theres a lot you can improve. and you will. for now, focus on your art; anatomy, gesture, lines, and colour.