I perosnally think you have reduced the saturation a bit too much , you need to as a little brightness to the face masks , try fethering when the masks are switched off dont over fether ( roughly 7-11 if you are decent with ur masks) this images is not very good quality also , try practising on High Res images instead, and yes for the shadowing add a curves layer and reduce it to the bottom , then you can see with a rough guid as to where the shadows should be , then you can make a black square and feather the places with a mask , this is not easy to do make sure you delete the curves layer after