If things are going to hard for one party…
try restarting the game :-)
If you’ve made one mistake early in the game, it’s possible you will see the devastating effect of the mistake you made some turns later…
here you can see it already:
apparently, your allies did not work as ONE team…
I believe that’s the first and best strategy to keep in mind!
Otherwise, I can only recommend reading soime topics at the forum :-)