People make the Byzantine start out to be harder than it is. Ally Poland, invade Ragusa, Urbino, Serbia and Bosnia, wait for the Ottomans to declare war, crush them. After your first war with the Ottomans, ally Austria and cruise to more victories.
Culture converting Anatolia is a requirement.
I can't be the only one that tries to maintain some semblance of historicity. I don't do anything that I wouldn't consider ASB.