Hi Madelaine,
1. It is a good idea to settle on a pose that is easy to hold when you plan for a long sitting. Try to find one that is easy to do, one that has good edges, some hard, some soft and some lost edges.
Apart from the nice hard edge of the left cheek our pose has mostly soft edges and almost no lost edges. It is difficult to define a face if there is that little variation, and the slowness of the watercolor proces makes it even more difficult. Sometimes you just have to wait.
I would have expected some lost edges under the head, by the neck and on the shadow side of the nose and the right eye.
I don't believe in the the light values in her right eye and the light on her right cheek sinse the light seems to come from above.
2. If the model is a real redhead then she might have very pale skin (a wonderful challenge for the painter) and it will look a bit bluish compared to the red hair. I don't think that the skin color looks wrong on the painting. The blue background holds the blue skin color back.
3. The alignment of the features, eyes, nose and mouth is a tough one on a sideway pose.
You saw my own problems on "Freja". I even noticed it and corrected it a bit on the first version, thought that it was enough, but it wasn't.
My suggestion is; find a pose with some clearly defined edges, hard, soft and lost, and some clearly defined values, light on the upside and dark underside. The hand could catch the light while the right underside of the face is dark. Things like that.
Look forward to the result.