Here are Light's guidelines for part of the Sharpening workflow.
This mask creation workflow gives you a starting point to build a very detailed mask to use in conjunction with your sharpening layer. You may go a step further and create an action to do this for you.
-Copy your background layer and rename the layer “Sharpen”
-Go to the Channels Panel and choose the channel (red, green, or blue) that has either the best contrast or is the best black and white image. Play around with all to see which you prefer.
-Copy the desired channel by dragging the channel icon to the Create New Channel icon at the bottom of the Channels Panel.
-With the “Copy” channel active, go to Filter>Stylize>Find Edges
-Invert the “Copy” channel by Image>Adjustments>Invert or by typing Ctrl/Cmd + I
-Remember the basic rule of masks – white reveals and black conceals. As you use Levels and your brush you want the image to be white where you want sharpening and black where you don’t.
-Open a Levels adjustment and increase the contrast by going to Image>Adjustments>Levels and move the white and black sliders.
-Paint with black or white as necessary.
-Go to Filter>Noise>Median and enter 3ish pixels.
-Blur the channel by going to Filter>Blur>Gaussian Blur and enter a value from .5 to 5 pixels depending upon image size.
-While holding the Control or Command key, move your cursor over the Copy channel icon and click the mouse, this will load a selection.
-Throw the channel copy away.
-Go back to the Layers panel and add a layer mask to your Sharpen layer.
-Sharpen the image. The layer mask will determine where the sharpening is effective. At any point you may paint on the layer mask with black or white to change the effective sharpening.