This doesn't look like pixel art.

78 colors so far... not a good numer. many colors were wasted in the skin and hair(actually half palette is browns and pinks), so i reccomend you to reduce your color palette. is not that hard, you just need to unify similar colors.

by the way, you have a serious porblem with the anatomy. while the face and torso are quite well done, the hair is messed, same for her left arm. the hair is so messed that it appears that it looks like you drew the face over some other drawing's hair because they don't match(either size and pose, they just simply don't match). its like a giant wig(?). The left arm is messed in his pose, a pose wich is basically unnatural. since its a 3/4 view, the left arm is suposed to partially 'hide' behind the torso in a way that only the elbow could be visible. the way you drew it doesn't match the pose of the image. D:

so, in resume, i would strongly reccomend you to use a good reference. colors are ok, but i would avoid that messy dithering you've used for the scales and try something more credible. the current one looks more like a mineral surface rather than a fish tail. there's a WIP thread around that worked in a subject similar to this(a japanese mermaid, if i'm not wrong), it maight be a good idea to check it and get some ideas on how to make those scales.

best regards from
Metaru