Now to the interesting part.
Select the upper (colourless) layer again, and go to Brightness / Contrast.
The idea is to reduce both Contrast and Brightness dramatically, so that the face won’t be anything but a background anymore.
you will get something like this (feel free to play with the settings, depending on a photo, maybe you will need less or more of brightness or contrast)
For the final touch, select again the layer below (colored) and go to Hue / Saturation. We will add a bit contrast, so that the eyes won’t be that “pale” anymore, and will blend in better…
That’s it. Hope u liked this small tut.