Honestly I think a strategy of absolute brutality and excess would be effective. The problem with the current US war techniques is this - it's half-arsed. Sure, they 'accidentally' kill civilians and 'accidentally' torture captives, but they also try to build schools and bridges and restore public order. They should pick one role and stick with it, either be an avatar of unbridled evil or an avatar of total good.
Blood flowing down the gutters in the corpse-covered streets whilst the agonised screams of the dying filter from the glass walls of the torture centres 24/7 would remind Iraqis of their place in American eyes - at the very bottom amongst the damned. Of course the problem with this approach is that the soldiers involved will be driven insane and become a liability, but assembling them all in a single area and dropping a low-yield nuke on them would prevent this problem from reaching home. The added bonus is that a city despoiled in this way would likely be never inhabited again, so you'd never really need to worry about terrorism returning.