Duplicate the background layer and go to Filter -> Noise -> Median and insert a value of 3. Next, go to Filter -> Blur… -> Gausian Blur … and insert 3 again.
Add a layer mask to the layer you just blurred, fill it with black and start painting with white over the skin, with a soft brush, varying the size according to the area. Make sure you avoid the lines of the face, eyes etc. because you don’t want to blur those, just the skin.
Switch back to Standard Mode by pressing Q again and you’ll notice a selection appear. The advantage of using the mask mode to select is that you have far more control over the selection than by using the Lasso Tool.
Go to Select -> Inverse and then to Image -> Adjustments -> Hue/Saturation… (or simply press Ctrl+U for the dialog box to appear) and insert the following settings:
Add a subtle highlight on her lower lip by using the Dodge Tool, a small soft brush, exposure set to 70%. With a slightly bigger brush you may highlight her upper lip, again in a very subtle way.
When you’ve finished, make sure the area of the lips is deselected to continue to the next step.
Step 3. To change the eye color, select the eyes by using the same method you used for the lips, and then press Ctrl+U to bring up the Hue/Saturation dialog box, check Colorize and use the following settings:
Press Ctrl+H and check for any mistakes. If there are any, fix them as previously shown with the lips.
Step 4. Now we’re going to do the eye makeup. Select the eyelashes on her lower eyelid by using the Lasso Tool, with a feather setting of 5. Go to Image -> Adjustments -> Brightness/Contrast… and lower the Brightness to -10. Deselect the area.
Create a new layer and paint with a purple, soft brush on it, over the area between her eyebrows and eyes.
Set the layer blending mode to Overlay and the Opacity to 35%. Then refine the edges of the area by erasing with a large soft brush around it, making sure it blends in well and looks natural.
Step 5. To enhance the effect of the image, we can now adjust its color cast to better match the changes we made.
Add a Selective color adjustment layer with the following settings:
Reds: -43 0 -22 +7
Yellows: 0 0 0 -41
Neutrals: 0 0 0 -7
Step 6. Add another Selective color adjustment layer, in order to change the color of her dress from cyan to purple:
Cyans: -100 +100 -100 +100
You will notice that this layer will slightly affect the color of the eyes. I actually liked it better that way, so I didn’t change it.
If you don’t like that, then choose a soft brush and paint with black on the layer mask of the adjustment layer (I’ve highlighted it with yellow on the following screenshot).