Joe's crop and elimination of the dress makes an alternate image to the original. As to "knocking out" the sheer curtains...that's a judgement call...eliminating the curtains removes the realism of the location; meaning quite simply that in the original, the tall city buildings that are hinted at gives this an urban boudoir feeling, while eliminating the sheer curtains entirely makes the shot become a generic white backdrop shot, one that could have been done anywhere...so...I disagree about stamping out the sheer curtains in a sense. The end result, the desired end result I should say, is what really counts.
I think now that you have a much more-capable camera, with a 2.7x larger sensor, and significantly better imaging capability, that you might want to think about exactly how you're going about shooting. I saw from another thread that you're using a prime lens, which many times will be "the wrong length" for the shooting environment's physical size. The new camera, and the new lens, and the way the focal lengths actually function in smaller, indoor spaces, means you can now shoot images more loosely framed, and crop off your borders, and allocate final spacing with much less of a quality loss than you could with the older D300. I mention this because you ask about the rules for cropping, and the old ways, the old opinions about cropping: I think one needs to be freed from rules regarding cropping, because frankly, almost any image can be cropped differently than the original in-camera aspect ratio, and a better image can be made through cropping. Some images crop exceptionally well, and may yield more than one image, and more than one aspect ratio.
The amazing thing about the new, 24-MP FX Nikon cameras is the image quality; it is now possible to crop 1/3 to even 1/'2 of a 24MP FX image, and throw away half the frame, and create a truly lovely image. It's possible to make a gorgeous 5:4 aspect ratio image, a 3:2 aspect ratio image, a 3:4 aspect ratio image, a 16:9 aspect ratio image, or a 1:1 aspect ratio image--it ALL DEPENDS on how the crop relates to the scene you shot! There is an old-fashioned 3:2 aspect dogma, the old idea of printing with a black frame around a 35mm film negative, with the negative carrier filed out, to create the so-called knockout borders, showing the viewer that the photographer was skillful/lucky enough to find an image that worked well within the camera's rigid frame aspect ratio,etc,etc.. I was educated/indoctrinated that way, but have now come to regard that POV/fixation as representing a rather limited, narrow-minded, ridiculous lack of logic and an utter lack of flexibility. If you want a series of images to share an aspect ratio, then it might be best to frame them that way, but be aware that such rigidity might really represent the old, "If all you have is a hammer, then everything looks like a nail" axiom.