I definitely agree with your commenters with regards to the placement of the model in this shot. The models pose is good but to fit the challenge she would have looked better in the distance with the train track leading the viewer to her. I am also wondering what would have been behind her if you took the image the other way, as it is at the moment I find the background too busy and distracting.
Technicals:
Portraits are not an area I know very much about at all but I will do my best to offer some advice. First of all, to me, the lighting looks very dull. There is no real detail in the models face and the colours don't 'pop'. It was obviously not the brightest of days so that hasn't helped here. Also the background has a slight out of focus look (it could be my eyes!), I would like to either see a shallower depth of field or have the background completely in focus.
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Isn't that a little trashy for a senior photo? Red high heels.. slit skirt showing plenty of inner thigh? In my personal opinion there shouldn't be any kind of sex appeal added to a photo that's designed to be displayed in a year book for children. The pose and choice of wardrobe just don't seem appropriate to me.
The tracks are good as leading lines and your subject is very good. I think I would have preferred she was back further so the tracks led the eye to her. The red is a good touch too.