Decided to see if I could get one of the nonpowers halfway decent now that I have a bit more experience. After a couple tries at forming Russia as a minor power (try forming Russia as Ryazan if you want hard, their only expansion options are Muscovy, Lithuania, or the Golden Horde

), and a failed attempt as Brittany, I seem to have established myself as a regional power at least as Bourbonnais. I'm gray in the picture (but not the same gray as Lorraine). AKA, I'm the one whose cities are all burning.
I often see Berri captured by the English under Henry V, so that was a concern early on. I devassalized nearly right away, while France was too busy to do anything about it. Then, midsummer 1419, France and England make peace for a small monetary exchange, and that includes me as I'm still in the alliance (just not a vassal). I then notice that Brittany also had the bright idea of canceling their vassalage (with England), as well as their alliance. That solves my sticky expansion situation nicely - I cancel my alliance with France, obtain right of passage with France (in that order), and after a few years (to let the truce after the initial war expire), declare war on Brittany. I take out one loan to fund a nice big army, and it seems they have the same bright idea as they're able to fund an equally large army to match mine, forcing me to take out a second loan. But in the end I subdue them and occupy all their territory, getting everything except their capital in the peace process. I could have made them a vassal, but decline as I want to conquer them later.
My main priority at that point was avoiding bankruptcy. I was already at my loan limit and if my creditors didn't think I was credit-worthy (I probably wasn't), it was tough potatoes. I had to disband two-thirds of my army to pay off one loan, and was able to extend the other

.
Well, just after I extended that loan, in March 1431, Auvergne declares war on me, bringing their master France and co-vassal Provence into the war as well, plus France's allies Scotland and Gelre. 19v4 in territories plus I'm already broke and have a 5000-man army. Not good. Fortunately the bankers think I'll be able to repay them somehow, and I get another loan to rebuild my army with. My strategy is the only possible one against these odds, a kamikaze strategy. There's no way I'm defeating France at this point, so I decide to target Auvergne, the leader of the alliance, and completely eliminate them. I occupy both Auvergne and Cevennes as quickly as possible, preventing them from training more troops. Meanwhile France, Provence, Scotland, and Gelre are sweeping up my territories, and it's quickly becoming do-or-die, rather than the initial do-or-lose-one-province. When I finish off the last of Auvergne's troops that are trying to retake their lands, I have 1% over the minimum number of troops required to besiege a city. So I take Auvergne itself, and then move on to Cevennes. Their alliance has 50,000 troops, whittling quickly due to insufficient supply lines, in Brest, my last outpost. But Cevennes falls first, likely only days before Brest would have fallen, and Auvergne offers everything they own including a healthy sum of gold, for peace as the leader of the alliance. Thus how I avoided total annihilation.
In the spirit of the fight, a Bourbonnais nobleman gave me 200 gold during the fight. Past when it was possible for it to actually help - I'd already lost all territories to the point that I couldn't train any more troops - but it was a nice gesture. Had a loss been inevitable my plan was to give it all to my old enemy England, but as I won it will come in very handy indeed to pay off those blasted loans.
Inflation, not surprisingly, is a significant problem for so early on, at 7.4%, and more than double the second-highest in the world. I feel like this is bound to be a problem with any small country, at least any that has strong neighbors. Still, it's better than the automatic +10% if I had gone bankrupt, which also would have caused other disastrous effects.
I still really need England to fight France again. Aragon is allied with England, which often leads to an English victory in the Hundred Year's War. Right now they're tied up in Ireland, though. Aragon has southeast Ireland and the Irish have more than enough forces to retake it as well as Dublin but aren't doing anything about it. Basically it's a stupid war that both sides would do best to end in a white peace at this point.
Biggest AI surprise thus far has been Novgorod holding their own in Russia. Mostly because Sweden decided to fight the Teutons and the Golden Horde invaded Moscow. Usually Novgorod gets completely dogpiled in EU2.