The important thing when exfoliating, particularly with facial exfoliants, is to ensure you're not over-treating. While the temptation is there to enjoy that amazing deep-clean feeling daily, generally speaking, once to twice a week is perfect.
For maximum benefit, exfoliate after cleansing. Apply product the size of a 20 cent piece to your palm and, using finger tips only, gently work into your skin in small circular motions. Be careful to apply only a light pressure, particularly when exfoliating delicate areas of the face. Rinse with warm (not hot) water and always moisturise to finish and protect.
I particularly love products that include AHAs (alpha hydroxi acids) in their formulation as they offer double duty; the AHAs (usually lactic acid from milk or glycolic acid from sugar cane) work to even out the skin on a cellular level, while the polishing grains perform their magic on the skins surface.
The result? Even, smooth, glowing skin.