In a basic way, Sharpening is a touchy subject. Lot`s of ways to get there, very much overused, IMHO, and easy to overdo. It is also very image dependant. Some images benifit greatly from some sharpening. It`s a good idea to sharpen some before reducing size, for instance. Some images are destroyed by oversharpening. Sometimes it`s just not called for.
SO, in short, if you can post an image, or part of one, we can give more specific instructions and suggestions on what it needs. (or doesn`t)
Also, a site search for Sharpening will bring lots of info, if general stuff is what you want.
Glad to help more specificly, if you`ll give more info.