C&C per req:
1. Nice! I like her pose here; stall, straight, this girl looks strong and confident like a winner should look. The lighting is good, and you've done a good job of maintaining distinction between three different levels of blacks. I do think a background light might not have gone amiss, and some minor skin smoothing is definitely needed.
2. Here I think you may have turned her body just a little too far from the camera; good head positioning, but I think bringing her body back about 15-20 degrees might have helped. You're starting to lose detail in the hair image left; a reflector might have been all that was needed for fill here.
3.Nicely lit, but she's leaning forward just a tad; I always ask clients, especially younger ones to 'push their chest out' that tends to straighten things a bit. I'm NOT a fan of the top she's wearing; bare shoulders & upper arms are rarely a good look in portraits, and what I find when I glance quickly at this is that it appears her top has slipped down.
4. Details, details, details! Watch the little things like the rolled hem of her top, and note the way the elastic is pressing it almost gives the impression she has a roll of fat above her breast; clearly she doesn't, but a quick look makes it appear that way. The shot'snice enough, 'but I think it would have benefitted greatly from some fill light and a slightly higher camera position.
Overall, these are a nice set, and most of my points are just very minor niggles, unlikely to be noticed by the client themselves.
Just my $00.02 worth - your mileage may vary.
~John