I ALWAYS do the kitchen first. For me, it seems to get me in an organizing mood since all the kitchen stuff goes in their neat little drawers and cabinets.
Then I move to the bathrooms. They are quick and easy to get done, so thats a mood booster there.
Then the bedrooms. This one takes a while. All the hanging and folding of clothes.
Save your decorations/pictures for very last! This way you have everything else exactly where you want it before you decorate.