Well, despite the belief that Tau are the 'dig-in-and-hold-out' kind of army, I always like to keep my troops on the move. I load up any Pathfinders and Fire Warriors I can into the Devilfish APCs, and my Stealth Suits, vehicles, and larger battlesuits give them covering fire until they can get to a location with moderate-to-excellent cover. Then I unload the soldiers, try to have them pick off some enemy grunts, and then it's back in the APCs and on the move again. Risky, but it works for me. Especially against armies like the Space Marines.