I think you've done a very good job with the final one. Why?
1.You've short lit it, which makes her face far more interesting. Short lighting has created the shadow that has slimmed her face nicely. Your other shots have been helped by her hair framing her face and slimming it, this one hasn't and the lighting has done the job.
2. She isn't smiling, which means that the lighting has worked pretty well, emphasising her high cheekbones and bringing out her beauty.
What could, IMO have been done better?
1. Her lips could have been slightly apart, it would have made it much more of a beauty portrait if they had been.
2. Her hair is generally dull and lifeless (same on all of them) except where the light above left has accidentally caught part of it. This portrait is crying out for a hairlight, it just needs to catch the top of her head - it's virtually impossible, and unnecessary, to light all of the hair when someone has this much of it.
3. Your light is far too low. Get it up, where it will shape the face better and make her eyes bigger.
4. I quite like your treatment of the background, but it's a poor choice of colour. The reason that naff patchy blue backgrounds are so popular is that they complement skin colour very well, everyone (regardless of their race or skin colour) has a lot of red pigmentation and blue or green is flattering. Red isn't, for the same reason.
4. We use matt makeup for a reason in photography. A lot of women wear shiny makeup for their own reasons (to get themselves looked at) but it is the wrong choice for photography, so in future get your models to use matt lipstick, not lip gloss.
Other shots
First one, pleasant enough but it doesn't bring out her qualities. Again, the light needs to be higher (on all of them) but because of the smile, this type of lighting has aged her. The answer is to get rid of either the smile or the shadows. An on-axis fill would have helped a lot with the shadows.Personally I always set the power of the fill as low as possible, and then gradually increase it until I'm happy with the result.
Second one, would have been good with a better pose. Her head needs to be pointing upwards towards the light, not downwards. Pointing it down has made her look submissive, insignificant and meek. And the lighting would have been better on her face if it had been pointing upwards too.
Third one. At least there is a bit of (accidental) light on her hair.
Fourth one: Same problems as the 1st 3, plus her smile looks odd. If people want smiley shots, try to get them to laugh instead, it usually looks more natural. Salespeople, airline hostesses and models are usually pretty good at smiling, most other people can't do it...
Hope this isn't too harsh.