I'm not too good with portrait C&C but here are a few things I noticed right off the bat. It's a bit hard to see where the light is coming from, because the hair, neck, shirt and background implies the right, but the nose implies it's coming from the left and the face says it is coming from above. Also you're nose is really throwing me off, for the entire body says you're looking right at the person, but the nose is saying that you're looking at the person from the left. Also some areas show a lot less detail than the entire project, (note that the direction for this next part is going to be from our perspective) the right inside of the hair, the shadow from the left side of hair, the upper lip, the shadow from under the chin, and especially the right shoulder. Also the background is very uninteresting, you could do a lot better (i.e. maybe she is in a fancy dining room, or maybe she's in a meadow). Bottom line is, this is a good 3/4ths mark for a finished product, just work out the kinks and that background stuff and you'll have a wonderful portrait.

EDIT: Two more things I noticed, the nose shouldn't be shiny, I noticed you added reflective light to the tip and that kinda gives off a wax coat look. Also the eye's shading is implying a a direct light coming from where we're looking at.

Yeah wow I need to go over this again and make sure I correct some mistakes. It was supposed to look like she was looking from an angle and I guess a background would be nice also. I got some spare time tomorrow so I can probably do it then. Thanks for constructive critisism (: I really appreciate it.