I'd say the colors are fine. The highlight looks like a headband though, and should extend to the ponytail too. Try to reduce the banding (layered lines of pixels) and consistency (making it go over the ponytail too)
Second, her arm swings on the side sprites aren't consistent with the front and back sprites. If the front and back are anything to go by, she should be swinging her hands well out in front of her. Remember, arms pivot from the SHOULDER when we walk.
Also, I notice that it changes position on her head on the front sprite. Pick where the ponytail goes and stick with it! I like it on the side personally, but it'd be less work to move it to the middle on that one frame. Do whichever feels right to you!
You've made an excellent start here, keep it going!
