before favors, 1444, sweden, ally england/novgorod/teutons/scotland, austria is awesome but needs to rival denmark
you cant ally all of them, it will be based on rivals
destroy useless stuff and build galleys, you want lots of galleys, also build to forcelimit
if you got england thats it, attack, scotland is hard, but they got boats too
denmark starts with rebels so keep an eye on them, denmark could lose to them or you could declare just as they are fighting on your border and then you snipe the danish stack with low morale and kill them
without a snipe you want lund mothballed, you will wait by skaraborg, you will move to tioharad in a way that they will arrive there by the first of the month, declare, and snipe the mothballed lund
from there take the rest of danish land and plant your galleys to cover the strait, then wipe norway
if you declare right away after a snipe you wont have the galleys ready, only leave port to kill lone boats, always keep two stacks in different sea zones so you can lure the enemy navy away with one, and move ever closer to the strait with the other, leave port on the final days of a siege so you get the bonus, then return to port before the enemy returns
if you go with novgorod, muscovy should attack soon, dishonor alliance then
develop till then, mark enemy lands as interest and get claims hoping for a war (let denmark lose manpower, save yours), get quantity
after favors i dont know (hopefully it doesnt use that system), it would take so long for anyone to bother joining your wars