Was this meant to be a serious piece of art or something humorous? Unless I know your goal with this art, it's a bit hard to gather my thoughts on this. It's at a crossroad where I can't tell if supposed to be serious or funny.
If this is supposed to be one of your more realistic or serious works, then I think one of the first things you should think about is the line work. I see uneven jagged pixels along the figure and it's crude in a way that doesn't lend itself well to that direction. On top of that, the head doesn't look quite right and the hand carrying the skull looks so simple and cartoony compared to the more realistic one on the right. A more serious work is usually better off looking cleaner with a good sense of anatomy.
If it's supposed to be a humorous or cartoony work like almost everything else you posted, then maybe you should've exaggerated it more and made her look uglier or funnier. The proportions of her figure are semi-realistic but they're off. I think you intentionally made her a bit weird looking, so it would've been better just to make it more cartoony artwork with whacky proportions all around.
If you want to improve this, then maybe study anatomy more and don't be afraid to look at lots of references, because it looks like you just drew from imagination. And also think about the line work as I've said before.
Don't let my low, critical score daunt you if you want to become an artist or want to take up art as a hobby. Keep making more art, learn new techniques and look at the artists you do like and study what you like about them. Improvements will obviously come to you that way.