Hi,
I know it's slightly outside of your control but I would suggest you ask models not to wear as much makeup, her skin in these images looks very false, I can actually see the thickness of the makeup on her. In addition, it's causing reflections from the flash, this is giving her skin the appearance of being greasy as well as giving some burnt out highlights in both images.
I generally don't let my models wear jewellery during a shoot unless it's for the particular pose, in these images I'd have asked her to remove the necklace, it doesn't add to the photograph and for modelling images everything has to have a purpose, without exception, otherwise there is a risk the images will look too much like snapshots.
On the first image:
I think the pose is very strong but I'd crop the left side so that the frame cuts through her hair, i.e. remove her shoulder entirely and crop the top so that the frame also cuts through her hair, about 1/3 of the way up through her hair would seem appropriate. The resulting position of her face in the upper area of the image would add real impact for a glamour style portrait.
The high position of the lamp has left a shadow under her hair to her right side, and has left some unflattering indentations in her skin on her left side, particularly around the mouth. In this case I'd have used a reflector to light up the left had side of her face without loosing the dramatic lighting. In my experience single lamp lighting only really works where the model has exceptionally smooth skin, or on guys where lines etc generally add character.
On the second image:
Again the makeup is causing shine to appear on her skin and if anything in this image her skin looks even more unnatural, almost mask like. What's noticeable here is that the position of the lamp has increased the definition under her eyes, particularly under her left eye where it looks like a thick mark on her skin. Again, the single lamp has lit up any tiny imperfections she has, in this image her left arm looks hairy as each single hair is being lit up.
Steve