(1) terrible crop - too centered and too much headroom. very "snapshot-y"
(2) underexposed subject. needed a very long lens for a tight headshot next to a larger sun to get away from the point and shoot look. sunset washed out.
(3) nice, natural light candid, but more negative space to the left is needed (as above poster stated).
The image has a picture of a very pretty woman with a beautiful smile. Nice expression.
The image looks OVER exposed (too light) and the skin seems pale and the colors look weak. She appears to be in a shaded area and yet the skin looks too bright, hair looks light, and the areas where there should be shadows appear "weak" or light.
The image looks like a few simple steps would greatly improve the image.
Try this (I assume you use Photoshop or similar):
1. Use a calibrated monitor to view and to do the editing.
2. Duplicate the layer (Layer/duplicate layer)
3. Go to the Layers Palette and click on the new duplicate layer to select it.
4. Look for the drop down box on the Layers palette. Click on it and select MULTIPLY (change mode to MULTIPLY) for the new layer.
5. Click on the slider on that Layers Palette (Opacity Slider) and move it to suit your taste. I recommend around 70%. IF you are NOT using a calibrated monitor, this will likely appear too dark. Remember, the hair should appear dark in shadows.
IF you do this you will see the face get darker and the colors of her skin tone and the surroundings and her garment get richer in color/tone. The image will begin to look more natural and "real" and colorful. She will look healthy. When I did this, the portrait took on a more "lively" character and on my monitor it looks like she is just sitting in front of me with natural light. Very pretty warm skin color/tone.
#3 is well exposed but as a result loses atmosphere that a darker exposure (brightness in background compensating and complementing) would retain I think. On fiddling with curves I lose detail in her hair but I think it's worth it.