It's a bit cheesy, but reliable: 1st turn - start some Vikings in training, throw everything else into Sweden. The Swedes will retreat without a battle and die off instantly. Your economy is immediately improved, you have iron, and you're one step closer to the Danes, and still only a single land border to defend.... Those v1 Vikings really help the Norwegian cause

I played the Norwegians on conquest mode, expert, and found it to be bit of a cake-walk, really. All those uber-viking units really kick some behind in early, and having Sweden soon allows you you tech up nicely before they become obsolete in 1205. I went west first, took over Britain and set up quite a trading empire. Got to about 50% of the map and went on to another campaign as it was too easy to steamroller everyone. But if what you want is a rampaging killing spree to work off the "dissertation blues" then the Norwegians are just the job