Iron Man: avoiding that one game ending mistake

Every Iron Man game I've tried so far, I've had to break off due to a fatal mistake that I wish I could undo. Some examples:

As England:

• Accidentally declaring war on Norway during a truce + allies Denmark, Sweden, Muscovy and France chipping in (clicked the wrong button after checking to see who would join them if I did attack them) ending in a loss of all territory on the continent followed by bankruptcy. Restart.

• Switching religion to protestant with all the national decisions to improve missionary performance. After the smoke cleared all overseas territories were gone, and even Scotland, Wales and Ireland. Set right back to 1444 and heading for bankruptcy. Restart.

• This time everything went perfectly. Burgundy was inherited by Austria, and thus not a rival for the first time. With Castille/Aragon/Naples, Portugal and an enlarged Austria as allies, we crushed France. I decided to occupy all their coastal provinces to keep them from colonizing. Of course I got greedy and did it again, cutting France in half and releasing Burgundy as a vassal instead of taking their offer to revoke all their cores on my territory. Threat eliminated, I thought. I thought wrong because of a coalition that formed against me as a result. I tried to take back what I lost with the usual allies, but this time somehow France + Tuscany just seemed to spawn unlimited armies with an endless supply of three star generals. How the **** did this end with a complete occupation of Austria, Spain, Naples and Portugal and a complete loss of all my overseas territory? Should have taken their offer to revoke cores.

I think it's wise not to try England again until I'm a bit less of a noob, so now I'm trying Castille. Any potential game ending pitfalls I need to watch out for? I have noticed a pattern of bankruptcy after unsuccessful wars. How do you all prevent getting into crushing debt? Surrender earlier? Any tricks to get the land force limits up?