Shaylle's Beginner Custom Sprites

I've decided to post this thread here, to show off some sprites I decided to make. I'm open to any and all criticism, and I'm hoping I'll be able to get better at spriting.

My first custom sprite started out as Bubbles from the Powerpuff Girls, and, it has pillow-shading, which is a shading style I dread. I wasn't really full of inspiration when I made this, so it wasn't going to be the best, and, it's one of the pixel-type sprites, where it has a complete black (or any other solid color) outline without variation. I made this last year in December.



The next two customs I had made were just for practice so I could sort of get the feel of it. They were both sprites of Sonic the Hedgehog, and they turned out horribly in my opinion. The sprites, to me, make me question my knowledge on sprite anatomy.



Another mistake I had made when making those two practice sprites were the fact I had used both pure black and pure white for whenever those colors were needed. Big mistake.

My fourth (third) custom sprite I had made was today, and I'm proud of it! I know I'll be able to do better than this one, though, definitely! It's a sprite of my friend's character, Darkie. I don't remember what species she was, but I thought it was the least I could do for my friend, since she was down in the dumps. (I used some Sonic the hedgehog sprites from other people to use as a size comparison. Why I used them? Simple: I had used them as reference for anatomy-based purposes.) Who knew she'd turn out to be taller than the three? Below that, I have a little time-line of the steps I did to make her, and right beside the drawing of Darkie (which my friend drew), I have the scaled-up version of the sprite. (This makes it better to see.) I also have a color palette with the original-sized sprite (finished) right beside it.



Hopefully there will be more sprites to come!