Thanks. :)

Alright, made one small, final change on the (our) right tip of Fiona's mouth. This is what I did: I extended the nose's shadow a bit, and added some shading to the tip of the mouth, and to me the smile does look more natural, but I don't know about you.

I hope I understood you right, since, as I said, this is the final change before the entry becomes locked to editing.

It looks a bit better, though to really sell the effect of smiling, the shadows would come from the direction of the nose, and the tips of her mouth would be just a bit off poking into them. 

Great improvement on the rest!

Okay, made some changes; while I couldn't do anything about the placement of the eyes, the mouth and the nose, I could tweak the shading. I attempted to shade it so there's as less pillow-shading as possible, but I think I kinda messed it up with the cheeks. I also thickened her neck a little, I hope it's thick enough now.

Please tell me what you think, and if I messed up the shading or something.

Well for one, your Fiona does not have any shadows whatsoever on the cheeks, which makes her face lack in structure. Also, the neck should not be thinner than the jaw, as the two are connected. You did follow certain details well, such as the shadows around the eyes and the one casted by the nose, but in the reference one side (shadows included) is significantly darker than the other. Good luck! 

edit - it might be frustrating to do, but the way I'd approach redoing the shading is by filling in the whole face as one color, then blocking in the shadows and highlights, and cleaning them up again later. 

I may not be correct, but Fiona's face especially looks pillow shaded to me, mainly because the forehead, and both sides of her face both have the same range of greens with highlights smack in the middle. 

Perhaps if you spent more time on getting the correct forms for each section (the placement of the mouth, eyes, and nose looks odd), the shading would come naturally as you would be able to see where the darks and lights are in your reference.

On the bright side, the wood texture is really simple up close, but at 1x it looks very convincing, so nice job on that!