For your first pixelart this is very nice stuff! Maybe it could use a little more contrast, but the witch and the ghost are really drawn awesome!

Thanks for the feedback, I will try to improve my work.

Welcome to PixelJoint! Nice picture, very cute! I saw your sketches on your site - you have interesting style. However, this pic has some probs: arms are different, as folds of her clothing; tone of broom is the same all over - you can't tell where stick ends and where threads start by color or by texture; different lightsources don't hurt much here, I think (but maybe you'll find useful to make the rest lit from left or use only lightsource from right); on some parts better to use less colors to make picture more contrasting and give it more volume (as on her hat - you easily can take darkest of your greys and replace lighter grey with it).