I'm considering starting this game (have to wait for it to patch when I get home) but I was wondering if any tips could be made available for a newcomer, I saw the video tutorials and read a guide or two on their forums, but it seems there isn't a ton of info for those who don't have experience with the game?

It seems as though the different nations have different trees, and thus need to be developed separately? If this is the case could I get any generalizations as to what each nation specializes in?