Good to see your still trying to improve! I will make one suggestion that I learned recently myself.
As far as being a pixel artist goes i feel like its better to learn how to do stuff with out a base. I mean its okay if you draw it on paper and what not but you should learn how to make stuff from scratch and not depend on other peoples work (like pictures and sprites bases) reference pics are good like for anatomy. But like tracing over outlines or editing outlines will only get you to a certain point. I am not sure how far you want your pixel art to take you.
But in order to level up and become a better artist I would suggest learning how to draw your stuff on paper. Trust me I suck at drawing stuff on paper but it is the way to go to learn how to do anatomy better and being more original. I learned this after years of spriting and doing it as a hobby. When it came to the point of me wanting to do it as a job and work on teams and stuff. Being original is the key! Learning how to sprite from pretty much nothing but your own imagination and skills is the key!
This just me but
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Try to challenge your self into improving your art! Doing more stuff from scratch is a hard process for people who started out just making edits. But in the long run it will better you!
I hoped this helped you! and Keep on posting your progress man