How do I get amazingly soft skin with OTC creams?

Water first. Take a warm bath and soak for 20 minutes. It is important that you not put any oil or bubble bath in the water--just the tap water. Get out and pat dry, leaving some moisture on your skin. Then apply a moisturizer on your damp skin. The heavier the moisturizer the better--use a cream or ointment, not a lotion. If you do this regularly you will have soft skin.
Skin creams. I am assuming you are asking how to use otc creams to get soft skin, or are you wondering why you personally are getting a great result with them? The key, i think is using the right thing for the right problem. And if it works but wears off then you should be using it a little more often. Also, getting a head start before winter dryness sets in can really help.