The shades of the skin are all so light the shading can barely be seen in 100% view. Shading a pixel work is different from larger drawings, you'll need more contrast to get the same overall impression. The upper front loop of the cloth is pretty good, the rest needs adjustment.
I wouldn use so much black pixels in the hair because it looks really noisy, also you could give more depth to the leg using darker pixels, there are some minor issues like banding and proportion, but dont worry because it is quite good if this is your first piece, keep it up! :)
Nice movement and pose, nice character design
but t he palette could use some work, there are too many colors and they lack contrast between themselves. Try working with premade palettes to get used to how the colors harmonize!