If you are starting out then you need to focus and target your efforts or you will go nowhere fast. so 1 product, until its automated and profitable then duplicate that method.
Generally one or two. it really depends on how much time you have to work on it. At least more than one because that one product could be a dud.
I use static (optimized) websites to promote 20+ different products. The websites don't need any maintenance so I keep building new ones every week. But I agree with others saying that if you start out then concentrate on 1 or 2 products (two may be better because this lowers the risk of stumbling upon a product that simply doesn't convert)