Playing as the Ottomans currently. I annexed all of the smaller nations to my east, as I had cores on them, then I allied Crimea, who blobbed a load in this game, so far. I conquered the occasional small nation to my north and west in Europe, but, suddenly, Serbia annexes Wallachia, Bosnia, Ragusa, Montenegro, Moldavia, and a lot of other small nations in that area. I'm stuck in a really odd position because the Mamluks have almost all of Arabia and, though I did end up annexing Serbia (they got into a lot of wars that they couldn't handle, so I joined in on the fun), there's still a super-Hungary to my north, and the Mamluks, for whatever reason, had half the size of my army, though they had a lot of eastern Africa and, as stated, Arabia. I managed to get a strip of territory down the Mamluks' coast, including Judea. A few years before the war with the Mamluks, I happened upon a very lucky personal union with (only had a royal marriage). Crimea is about my size (well, province-wise, only half), so I'm sitting with a lot of territory. Only real issue is that I am behind a lot of techs in administrative because I have to core and change the culture of a lot of provinces at all times because I'm going for at least a conquest of Europe. I'm keeping up in all of the other techs, though. I currently have the second best army and one of the top navies (maybe the best, not sure). Pretty good so far.
Edits: Surprisingly, aggressive expansion isn't actually all that bad. I'm much more powerful than a lot of nations at the moment, I'm able to stomp all rebellions, and when I get the aggressive expansion penalty, it only really affects the nations that I don't care about. Otherwise, the ones that I do care about already love me. I've, indeed, run across a few coalitions, but they seem to never honor the coalition alliance (very odd) or leave the coalitions, so they aren't really issues.
. After 5 restarts (Ironman mode fails) and 6 hours later, I decided to change my early strategy. I used a mission to gain core instantly on one of Korea's province at the start, before Ming could warn me not to go to war. I then spend all my diplo points and took as many provinces as possible from the first war. The day Ming's warning expired some 20 years later, I slowed down and paused the game then declare war on Korea once again, this time to annex them! At the same time, some 23k stack Manchu rebel rose up against Ming, who was still busy fighting the war with Dai Viet/Shan and rebels in the south. Surprisingly enough, the Manchu rebel stack managed to capture 2 of my cultural province and defected to me! Now I just need Beijing to use the "Qing Dynasty" decision for some base tax bonus and cores for all of China!!. Looks like I'm off for a good start this time 
