High Pass Sharpening

On the Layer Palette select Background Layer and right click.

Select Duplicate Layer

With this Duplicate Layer highlighted -

From the Filter Menu and Other select High Pass

Set the radius to 10 and click OK

Back in the Layer Palette select HARD LIGHT from the drop down menu

In the OPACITY SLIDER select a sharpening level that in your opinion gives the best results. This is usually between 20% and 70%