Thanks for your comment and advice!

This is really important for study. And yes, agree. It needs work. I think to redraw it someday from the beginning.

Sorry for answering for so long. Wasn't here for a while.

Cute avatar! In my opinion, it might be better to replace the dithering (checkerboard pattern) in the ears with larger clusters of a separate cluther. I know that they're supposed to be hair / fur, but it doesn't quite read like it, in my opinion. There's also a fair bit of banding in this piece (not sure if you're familiar with the term, you'll find it in pixel art turtorials) and I think it detracts a bit. Nevertheless, cool piece! :)