That squatting pose is really not good delete it from your shot list, very very unflattering to the poor girl
Also try not have straight joints like the main supporting leg where knee is locked solid
and get her to wear heals it will make her poses a lot better due to creating better shape to her legs
Search for some posing guides there is a lot of resource around on the net get a few good poses and practice those shoting at different angles
I was about to write the same... the pose on #2 is a no no.. seriously...
OK. I'm far from pro too so my 2Cs...
The others are too centered. Nice model but doesn't show much interest and the not too interesting backgrounds add to that... next 2 are better as far as the smiles but again the pose, the composition, the backgrounds "ruin" it for me.
Think about why, where what you shoot. What light, backgrounds you are using and what would you like to achieve with them. Think about composition. Be strict with yourself. Don't be afraid of getting rid of photos that are not your bests.. of course this will continuously change as you're getting better and better.
Try more than one versions (DOF, light, comp).
If you haven't done it yet look at videos on youtube. This is a pretty good place: http://www.youtube.com/user/adoramaTV/videos
but only one of the many good ones..
If you are interested in portraits it would be a good investment to get a good lens preferably in the f1.4-2.8 area... even if it's a 3rd party... I always said lens 1st bodies 2nd..
But the most important... You're heading to the right direction just Keep shooting!