First off, you always want to make the improvements before the shot, not after. The "darkroom" be it the digital or traditional version should only be used for minor tweaks and fixing small details. That said, C&C per req.
1. The lighting on the left side of her face is a little harsh, while the right side is very dark. A diffuse fill light aimed up, at right side would have helped this. Always look carefully at your model just before you're ready to shoot; in this case the strand of hair that curls back up on her shoulder looks somewhat out of place. Also make sure she's looking at you; in this case the image leaves me with the impression that she's looking at someome well off to the side. Finally, the pose is rather stiff and effected.
2. The focus is a bit soft on this one. I can't tell for sure on this less than perfect work monitor, but it seems to me that it might be due to camera shake. The pose is fine, but her dress is a trifle bright (a quick levels tweak would fix it right up) and appears bunched around her waist. Finally, there's a bit of bra strap showing at her back.
3. Again, a bit soft on the focus, but other than that, not too bad.
Overall, some good potential in these pictures.