I figured it was easier to show my critique than to explain it, so I did an edit.
The palette was the biggest thing. One reason she looks like Mrs. Claus is because of the oversaturated red you used. In general, for dark colors, never have full saturation; it's loud and looks bad. You also didn't do much hue shifting. When I changed the palette, I both reduced the saturation and slid the darker colors towards purple and the highlight towards orange--you typically want highlights to be warmer than shadows. I also put more red in the scarf palette to make it look more unified. Look at how I arranged the palette. Both the red and the lavender use the same darkest shade, which both makes it look unified and saves you a color (there's no reason to have a bunch of very similar darks). You could also use the lightest lavender shade with the red if you wanted because it's yellowish. If you're using Paint to sprite, get a better program that offers you more palette control, like GraphicsGale (which is also free, it should be noted).
Another thing you want to keep in mind is anti-aliasing, which is softening lines with similar colors around it (Google it if you're not familiar). You tend to have the darkest color at the border of all your objects, which both kills a lot of the depth you could have and tends to look choppy since you're not AAing to the edges. Look at what I did, particularly with the scarf around her chest, to get an idea of what I mean.
Now, for the other changes I made. I got rid of the midriff both because I find heroines adventuring in skimpy outfits ridiculous and because the light color was somewhat confusing with the scarf directly above it; the way I have it makes the scarf much more readable. I also adjusted the scarf so it was covering her boobs better, which I think was what you were going for. I pleated the dress as long as I was there because I thought it looked nice and the way you had the miniskirt before didn't really convey the shape well. I changed the ends of the scarf because the way you had it before made it look like the lower part was some kind of glove. I also clarified the shape of the feet and the hands (although admittedly what I did to the gloves was pretty lazy, so uh, play with it more).
I didn't mean to change the skin color, but whatever, I like it better. The midtone you have there is very washed out.