Pixel Effect

First make a new image. I will be using this image.

Now you need to duplicate the image. Next, go to Filter->Pixelate->Mosaic.

Quick Note: I suggest placing the cell size somewhere between 25-40, but it all depends on your personal preference.

Now you need to set the opacity to a lower level. I set mine to about 45%. You can set it to whatever you think is better.
Now you need to erase the vocal points of the image (i.e. the face).

Now you should have your image, here is how mine turned out.