Christie, would you mind picking either 3 or 4, depending on which you think is stronger and give me your thoughts?
First, thanks for the kind words about my site.
3 and 4 are virtually the same, so the following applies to both. If I had to choose one over the other, I think I have to go with 3 as her eyes are more open... even though 4 has a bit more foreground.
As already covered, what strikes me first is the color balance. I prefer to print people a little on the warm side, but this is much too warm. And you have light of differing color temperatures. It's most apparent on her forearms where the light is cooler.
Next is the quality of light. You have her in direct sun, creating hard-edged shadows. Shadows are necessary to communicate shape and texture, but a softer, diffused light source (like the open sky) will cause softer shadows, more flattering for portraiture. And, it's likely the ratio of highlight to shadow intensity would be less (shadows not as dark).
Her hair is a wreck. A brush would have done the most good. Also, pull it back off her neck. Have it fall either in front of or behind her shoulders, and not clinging to them.
The pose could be refined. It's a good start, but move her elbows out and away a bit. This will give you diagonal lines rather than vertical, relax her shoulders and allow her to bring her hands in closer to her and away from the camera.
I like the framing in 4 over 3. The building in the background isn't adding anything good to the composition.
The 50mm is fine for full length, but a longer focal length would help here. You'd have less distortion and fewer background troubles.
Finally, the wardrobe. The long-sleeved V-neck is a good choice. I would like a tone that photographs a bit deeper than her skin tones. That little crimp at the V of her collar is distracting. I usually ask her to make this kind of adjustment. A necklace might have been nice. I advise customers to remember to accessorize, mentioning ear rings and necklaces.
And I don't know if you did or not, but once I get this far and have my ass down on the ground, I make a full range of expressions. I explain they will have the opportunity to reject any smiles later, but let shoot some so they will have that choice.
I hope this helps.
-Pete