I have been trying to prioritize military tech advancement whenever I can, but my annexations of Teutonic, Livonian, and Hungarian territory has lead to me having to use the harsh treatment method of preventing uprisings from occurring. Muscovy is weak, because I have been supporting Novgorod, but I haven't really done anything about the Ottomans yet, aside from allying Austria and vassalizing Transylvannia. Ottomans aren't strong yet, but they can get there. Right now I'm sitting at a point when the uprisings are for the most part dealt with, but I can't destabilize my country much more, I can begin westernization if I want but I don't want to lose stability, and I'm 1 administrative tech away from forming the commonwealth. So need to figure out the right order for all this stuff without causing any rebels to rise up and keeping enough allies to keep Denmark, Muscovy, and the Ottomans away from my lands.
edit: My latest playthrough is now with the Wealth of Nations DLC, on top of Art of War. I looked at cossacks, but it didn't look appealing, and a lot of people were saying that it changes the game too much. So I opted for a more popular DLC, and a cheaper one.. So far not much different, but I didn't really expect it to be, as the focus is on merchant republics or whatever.