This Photoshop tutorial is designed to instruct on the proper use of Photoshop's Unsharp Mask tool and 'Sharpen Tool' (R) to fine-tune the sharpening level of your photo without over-sharpening the entire image.
Sharpening Digital Photos
Any time a photo is re-sized it will need to be sharpened, as the algorithm designed to re-sample the pixel information has a softening effect. Too much sharpening can lead to an unnatural appearance, and too little can leave a photo blurry, vague, and undefined.
Quality sharpening cannot be done with Photoshop's basic 'Sharpen' or Sharpen More' commands, as this is a one-size-fits-all approach that does not take into account the subject-matter in your photo, and the amount of re-sizing to be done.