Diffuse Front Wall? Absorb rear wall?

I'll research existing threads, but quick basic question --- is it a basic tenet that I should use a diffusing approach for the front wall and an absorption for the rear wall behind my listening position? I bought a wall rug, put it on the front wall, and though it seemed to quiet the room down in some good ways, it seems to have sucked some of the energy and sparkle from the soundstage. thanks.