First thing I would do is tell her to take a bath before a photo shoot. Secondly you should find a more appropriate photo for a public forum. I don't like being a prewd, but we do not know how many minors view this forum.
If you still want to fix this digitally, then the healing brush will become your friend.
The Healing Brush is an intelligent paint brush that is similar to the Clone Stamp tool only in
terms that you sample from one image area by option (Mac)/alt (PC) clicking on a source
area and then paint to cover up blemishes, wrinkles, scratches, or image damage.
When the Healing Brush samples it “looks” at the texture, color, and luminosity of the
source area separately. Then when you paint it merges the texture from the sample area
into the color and luminosity of the destination area.
To create a seamless merge i.e. retouch the Healing Brush spreads out by10-12 pixels
around the brush. This is an important tidbit of information to keep in mind when using the
Healing Brush. Due to this built-in spread it is recommended to use a hard-edged brush
when using the Healing Brush.
The Healing Brush can only work on layers with actual pixel information i.e. the background
layer or layers with pixel data. This means that you cannot use one of my favorite Clone
Tool techniques of adding an empty layer, checking Use All Layers in the Option bar and
healing onto the empty layer. To work around this detail I suggest that you generously select
the area to be healed and copy it onto a new layer (Layer > New > Layer Via Copy) or
command/control J and then lock the layer into position by clicking on the small lock on the
top of the layers palette.
Mike with Curvemeister has (or had) several tutorials on skin tones. Many used his product, but some did not. He also had many Presets for various skintone types. I have not been to Mike's site recently, so cannot tell you exactly where the tutorials might be. He was also a very valued contributor to this, and several other fora.