I am not experienced in pixel art as many other memebers, but i can give some advice.
I started making sprites for a Terraria mod and my first work was a resprite. It was really bad, but i just enjoyed the process of making such stuff and this is how i got into pixel art. I learned how to animate different mobs, items and i was free to use my imagination. The only thing that i had to consider, was the art style of sprites sprites (black outline for example). Size and color were mostly free for the artist. Those were fun times and i got pretty decent knowledge.
After some updates, the modding community went down and i went onto some android games. I choosed Pixel Dungeon, whit its friendly modding community and do sprite work for mods even today. Pixel Dungeon had some cardinal changes to the way i should make sprites. Those were the tiles/items/mobs sprites, that were only 16x16 pixels max. Making items, good looking mobs and animations- it was a big challenge that i sucessfully mastered and became really good at small sized sprites.
Then i tried some different different sprites "styles" and working on perspective. Now i am working on some big projects that can be called pixel ART and it's pretty cool to try out new things.
As you can tell, i was learning almost all by myself, but used some examples to learn animation (moving especially), shading was easy for me . It is only a little bit more than a year, since i started doing pixel art, so i have a long way to go and you have a long path as well. Feel free to learn any way you want and you will become a great pixel artist. I belive in you )
Best wishes
Pavel