[j sotelo]

Unsharp Mask Filter:
Photoshop has various Sharpen filters, Unsharp Mask and the Smart Sharpen Filter give the most control over the sharpening process as you probably know it gives you a range of sliders that when adjusted it alters the way the effect is applied to the picture.
its a good way of making your scans and pictures clearer.

Amount:
controls the strenght of the sharpening effect, a larger number will produce more pronounced result.
values of 50% and 100% are suitable for Low Res. Images 150% to 200% for High Res. Images.

Radius:
This determines the number of pixels around the edge that are affected by the sharpening.
A High number can make a noticeable halo effect around the picture, a Low value only shrpens the edge pixels.

Threshold:
This is used to determine how different before they are considered an edge and therefore sharpened.
A value of 0 will sharpen all pixels in the picture and a setting of 10 will only sharpen the areas that are different at least 10 levels or more from the surrounding pixels.

I found that one of the best ways to apply it is by doing it thru the Lightness Channel,
1.- Image > Mode > Lab Color
2.- In the Channels Palette click on the Lightness Channel, and in this Channel you can apply the unsharp mask.
(you apply it to the Lightness Channel because it contains the details of the image)
3.- When youre done go back to Image > Mode > and now convert back to RGB Color.

Hope It helps !!!

[simpbow]

Some very helpful tips there Sotelo that i could use, sometimes i think my sharpening could let me down, cheers & have some points for your tip.