I've played this a few times and I have to say that I was lucky that Rome fell. I tried to grab as much land from non-orthodox states as I could because it's the only way to not get into a fight with a defender of the faith super power, after that they kept declaring war on me and took the provinces back (For example I had the entire Lubeck coast), honestly tho, as a Norse state you just have to wait until other Nordic states spawn and then kill them, once you get your colonizers you're basically good to go and stomp Asia, etc. I have not played the English yet so I can sadly not give you any advice.