I also use the High Pass filter. I create a duplicate level (ctrl-J) adjust the pixels to between 2 to say 5 - it is very judgemental. Then go Filter> Other> High Pass.

This will grey out most of the image. On the Layers Tab, change Normal to Overlay. This will make the photo appear more natural but he changes that you have applied will be visible. By clicking the on / off eye icon you will be able to see the effect of the sharpening on your layer. You will be able to adjust this by using the opacity slider.