It really doesn't make much sense to most but if you want to clean your face - DON'T USE SOAP, it will only clean it TOO MUCH. What does that mean? Well, soap will strip your face of its natural oils and moisture. So although your skin will feel fabulously clean, you are actually damaging the skin by leaving it unprotected. It takes time for this layer of protection form, so you are only leaving it open to damaging pollution, etc.
To cleanse your face, you can purchase cleansers that contain milk or even make some at home.

Tip: If you are using a product that leaves your face feeling tight or itchy, discontinue use. And whatever you do, if you want to clean your face - don't use soap!