Im pretty sure ive mastered noble, but im unsure about moving up a nother difficulty lvl. Can anyone recomend a good civ to start out as I understand that some civs are better at higher lvls. I tend to enjoy quite a bit of warmongering but is that still possible at higher lvls? So far my favorite civ is Russia/Catheryn for the cossacks and financial. I normaly play a game on standard/normal speed. Any advice would be much appreciated.

Catherine will be great above noble too.
And keep your warmongering skills in shape -- you'll need 'em even more :).

Try China - Industrious & Financial. You can really crank out the wonders, half-priced forges, and the financial benefits.

If you want to try some early warmongering, give the Romans a go. The Pretorian is unstoppable.

As an added challenge for noble, try the Tilted Axis maps or with some of the other game options checked, e.g., agg. civs, random pers., raging barbs, etc.