My leader died in my last game as western romans in battle (big mistake on my part), and I was stuck with a barbarian leader since he starts off as heir to the empire. I considered that game over. Didn't want to play as a barbarian. Granted, I could have waited for the true roman's sons children to grow and try to assassinate the barbarian family line, but was too disappointed to keep playing.
So, doing eastern romans and its pretty hard. A LOT harder than western romans. My first game, Sassanids pwned me. Second game, Sassanids pwned me. Third game, Sassanids pwned me. Fourth game I bribed Sassanids, but then everyone else pwned me. And western rome declared war on me, so I just gave up at that point lol. Western rome didn't like me for some reason in that game. Dunno why people say western rome is hard, it IS if you don't burn everything to the ground. But the way I played western rome and consolidated in italy (burned everything else, including africa) made it a lot easier to play. Granted, I could do that as eastern romans, but it doesn't feel right and I have a ton of rich provinces that I'd really suffer.
Finally, fifth game I got my eastern roman leader a marriage with a Sassanids princess who is also fertile (20% increase chance of children) and bribed them like heck. Now I have a defensive alliance with them as well. Before the alliance, Attila declared war on me (wish I was able to get the alliance sooner). But, I've gotten a TON of my allies, including western romans to declare war on Attila. Attila is at war with a ton of people and has even been pushed back by the sheer might of defensive forces. I'll probably get sassanids to declare war on Attila, once I go back on. They like me a lot
just gotta give them money probably. Money buys anyone
I have declared war on a couple Sassanid enemies too, which raises relations a lot. So that probably helped a lot in getting an alliance from them.
I also destroyed all the churches, and replacing it with roman pagan stuff. One reason I haven't expanded really, is cause I want all my provinces to be roman pagan.
Mostly I've let my allies do the work. Plus I made a few vassal states, otherwise I've been building up my cities and economy, playing heavily diplomatic/economic focused. While I'm not blitzing around the map, its actually worked out really well and my vassals have even taken territory on their own. A really fun change of pace from just conquering and blitzing everywhere.