First correct the yellow cast. For the shadows, you can duplicate the image and use the clone
stamp set to lighten mode. Soft edge, 100% opacity. Sample from the light area and clone
onto the shadow areas.
This will take out all shadows, including the ones you need that show the contours of collarbones,
shoulders, etc. So after you remove the undesirable shadows, you'll have to restore the useful
ones. Dodging and burning can do that. (Instead of the dodge/burn tools, I use curves adjustment
layers in luminosity mode.)