I agree with Derrel, this type of stuff is really getting popular. I really, really love the work of Robert Alvarado...he is probably, at least partially, to blame for the recent popularity of pin up. If you Google 'Alvarado Pin Up Technique'...you'll get tons of great info.
One technique he often uses, it to completely cut the subject out and use a digital background. Usually just a solid color with a circular pattern. That would solve your shadow problem.
I also agree that the pose is lacking here. The head (chin) jut that Derrel mentions is a big one. This is something that will improve the pose/look of most people. Unfortunately, it's an unnatural thing to do, so you have to show your subject how to do it, and then remind them to keep it up...every minute, because they will forget or let it relax.
Also, her pose could stand to be a bit more feminine. By that I mean that you want to create an S-curve with her body. So things like a bent knee, sticking out her hip (bend at the waist), sticking out her chest & tilting her head. Some or all of these things can help to create that curve. It only needs to be subtle...and you may have a bit of it going on here...but to me, it looks more like she's standing up straight in a confident masculine pose. Nothing wrong with that, heck, it's practically politically incorrect to say that a confident pose is masculine...but this isn't a business portrait, it's Pin up, and I think that femininity should be the goal.
Back to the pose, she has her weight on her leg that is closes to the camera. This adds size to that hip & thigh. A common rule of thumb for women, is to have their weight on their back foot, so that the closer side looks slimmer. This also allows the front leg to be bent, helping to get that S-curve.
Lastly, her hair looks almost featureless...in other words, it's too dark and needs a hair light. And I think someone mentioned the stray hairs.