Open your image.
The fist thing we did was cropping the image.
Next step is to duplicate the background twice. Set the upper layer to the blending mode Overlay.
Convert the top layer into a smart object
Then go to Filter > Other > High Pass and choose an amount around 15px - 20px (depending on the image you are using) and click OK
Press Cmd I to invert the top layer (ctrl on windows). Now the image is blurred. If the amount of blur is too much you can change it anytime, because your layer is a smart object.
Now we add a black mask to the top layer (holding Alt and click on the mask icon in the layer panel).
With a soft white brush we paint over the skin to add the blur. Don't paint over the eyes and the mouth. If you paint over areas where you don't want to have the blur, paint over it with a soft black brush.
Its fast and easy.