Photoshop - Unsharpen Mask

Here is an interesting chart for unsharp mask on


Subject                     Amount   Radius   Threshold
Soft subjects             150            1            10
Portraits                   75              2              3
Moderate sharpening 225       0.5              0
Maximum sharpening 65        4                 3
All-purpose sharpening 85        1                4


Source:
For starting values of the USM filter for different uses, try the ones suggested by PhotographyJam:
http://photocritic.org/unsharp-mask-sharpening-photos-photoshop/