Place your less capable tanks (such as T-72s) on the reverse (that is, opposite) side of the hill from an enemy advance. The enemy won't be able to see the tanks until they crest the hill, and then the T-72s can pour shells into the enemy at close range--hopefully negating any technological advantage the enemy has. That's the theory, but it didn't work too well for the Iraqis at Medina Ridge.