Since I just joined the website I can't really be that good at providing you any good tips to make it better. But I have been playing games for a couple of years.

You should most likely make variations of the sprites, not just the colors. Maybe make one with her arms out or something like that? If you don't wanna do that just make subtle changes to them, change the color of their eyes or maybe the hair as well.

Good luck with making more pixel art and making that game.