Never played the original CK, but in CK2, I try to stick with my ancestral homeland of Ireland and proceed to take over britan. Or try to, at least. Usually through various underhanded methods, of course.

Or go with my favorite Norse Vikings and attempt to reform the Norse Pagans into a proper religion and push out those catholic scum and their heresy xP

It's been awhile since I've done it though. I remember it not exactly being easy, though xD