>>2582711good concept poor execution OP.
>I did a pin-up-style shoot1) the shirt covers too much for a pin-up, unbuttoned and tied in a Daisy Duke fashion exposing her midriff would have brought some sex appeal without showing too much.
2) the camera's engagement with the model is severely lacking, sure she is in the photo and sometimes looking at the camera but the vibe that is coming from her is "why the fuck am I here?" it is like you either didn't talk to her at all or you or her were nervous and just made the shoot awkward.
A few ways to get around that awkwardness:
a) beer or wine, you would be surprised how far a glass will go
b) work with an Art Director, Stylist (hair / makeup), or a flirty assistant to be a neutral party
c) work with a professional, Pros know how to work a camera, all you have to do is get the lighting right compose the shot and press the shutter.
3) I don't know about the colour of your seamless, even more so I would consider desaturating the whole thing a bit.