Hmm, one thing that hasn't been mentioned, is how you've colored your sprites. I think they're in need of a little variety as far as the hues and saturation go.

vs.

Then again, there are other issues too, such as the way you light your clothing for the witch doesn't match the way you shade the character's template's arms and face. The hair also doesn't quite adhere to the light source, and, as a result, the arms, face and hair stand out from the rest of the picture in a not-so-good way.
I tried fixing the lighting, but failed. Oh well. Take my advice for what (little) it's worth.