A little patience, I hope.
We occupied Japan for seven years before we left entirely. Let's hope we have a little more perspective on how long things take than was shown by many about the length of the military campaign.
A short bit on the occupation of Japan can be found here.
I dare say we will do a much better job this time. I expect we will do a lot less forcing of policies on Iraq. I hope that's a good thing. Sure as hell we did a lot less damage to Iraq than we did to Japan.