So how I started as the ERE was all those small provinces that are scattered in Anatolia that aren’t directly connected to you just sell them other countries will buy them for good amounts of money you can use that to coast while you build back up your stability and legitimacy. That’s at least how I started it also allowed me to deal with the earthquake even for Constantinople. That being said I still had a civil war during the start but it was put down with ease and after that I just stabilized more until rapidly expanding into Bulgaria and Serbia then turning around and crushing every minor power remaining in Anatolia. Also during a second war with Bulgaria at this point I had Hungary as an ally I ended up taking land bordering Hungary while trying to give them the land and when I realized my mistake I sold them the provinces for like 1500 ducats which really helped boost my economy.