Cleansing of the face is very important because are faces have sebaceous glands that make sebum. This is a oily substance which protects the outer layer of the skin. The skin on the face is exposed to many harmful chemicals that are in the air, such as cigarette smoke and dust. With all of the grime, you would think that we would have to cleanse very aggressively.
Never use the soap that is used for cleansing the body on your face. Soap that you use on your body is far to drying for skin on the face.