Well, from one wildlife photographer to another...
They all look nice and sharp, but the lighting is a bit harsh. I think with some work playing around with the ideas may improve them. Also, unlike wildilfe post processing work is pretty key with portraits, with a lot of cleaning and heavier processing.
In the first one, I find my eyes being drawn to the bright areas behind, particularly because of the pointed shape that looks a bit like an ear. Sometimes it's good to go in close, but I think you're caught between too tight and not tight enough with this one. Try a few different crops to see what works and what doesn't. Cropping tighter will help to remove the distracting elements too.
I like the lighting on the second one, the slight rim lighting on the hair works well. However, I think at this angle, the hair over her left eye doesn't quite work for me. It certainly works for some shots, but I think it's more with moody looks, than head on with a radiant smile.
I think the third one is my favourite, but the harsh lighting doesn't help it. Her nose is too bright and I'd like to see her eye less in shadow. Try playing with the sliders in Photoshop or Lightroom if you shot in RAW, as I think you could reduce the contrast, then you may need to do some dodging and burning in the TIFF. Compositionally though, I like it, although you could perhaps crop out the little bit of her other eye.
The last one I think is an "almost" shot. Again, playing around with the highlights and shadows to reduce the contrast will help a lot. I think cropping the edge of her eyes though has lost the impact the shot could have had.
Hopefully my comments help until a real portrait photographer comes along.