C&C per req:
Quite the dichotomy here. You've got a very pretty model, and you've done very well on couple of the most difficult aspects of portraiture, that is sharp eyes and good lighting. However there's one area where your images, to be polite, fall down, flat on their face. Backgrounds. In all cases the backgrounds are messy, distracting and really detract from the picture. Even if you're very limited in your choices, a plain, light-coloured wall would work. In general, try and look for homogenous backgrounds with a darker, contrasting tone to that the of the model and his/her clothing. That's all minor however, since location is easily fixed.
Just my $00.02 worth - your mileage may vary.
~John
That, is, in my opinion, a suggestion for a suitable background. Since photography is largely subjective, if those backgrounds work for you, that's fine. Personally, I don't see the attraction in a chain-link fence, dead leaves, and concrete, but that's me. With respect to other points on your image, I'd say you've done well, but your not at the "all it needs is a different background" stage by an means, and nor are most photographers (myself most definitely included). There is always something we can do to improve our work. I chose to comment spefically on backgrounds, since, they were, in my opinion, the major issue with the images.
Your post isn't bad, however I'm hesitant to make too many comments on it, since my already crappy work monitor seems to be going further downhill. A couple of things that I notice is that in 1 and 2, her face seems a little soft; thay may be slightly over-zealous post or it may be that the point of focus wasn't bang on. Also in #2 her faces seems a little whiter than in 1 or 3.
As far as poses go, in #1, she's too close to the RH edge. If you're going to shoot portraits in landscape aspect (and that's fine) just make sure you don't jam the subject all the way over to one side and waste a large amount of the frame on empy space. Also be careful when composing / cropping to avoid cutting little bits of limbs off. If you need to cut / crop a limb that's fine, but don't do it near a joint, don't bisect limbs along a longitudal axis (left shoulder image #1), and avoid little bits being cut (right hand fingers #s 2, 3).
Again, just my $00.02 worth - your mileage may (and probably will) vary.
~John