Trying to add to my world, ideas welcome

1) You have to have idea of what it is you want to write about. Internal politics? International politics? Wars? Etc. That will give you idea of how large your world has to be and what you have to have in it. Also, what is the social system? Roman Empire? Feudalism? How does political system work?
2) Is it alternate history of our world, inspired by our world, or something completely original? (Well, last is impossible)
3) Try to learn from history, fantasy etc.

I cannot really help you without knowing more details about your world.

 

In that case you need to have a fairly detailed worldbuilding.
1) Are you focusing primarily on international or internal politics?
2) What are internal politics of these empires? How do they affect international politics?
3) What are important houses? What are important individuals?
4) Relations between houses and individuals? How do these affect internal politics? How do they affect international politics? How can/do nobles take advantage of international developments to promote their own interest? How do internal developments affect relations between the states?