In my experience it's best to recognize if you should be on the inferior side of things or know where or how someone else would "give". In most cases on my end and among the people I RP with we establish if we're going to fight ahead of time. As we work up to the moment we may have figured out details on how we want it to go so we can work it into our story with questions like, "How will this enrich my writing?" worked out.

In the case of something like Precipice of War we've had the idea that we need to kick up the major second Great War for a while. The RP was built on the idea it'd happen. But it took four years to get to it somehow because previous suggestions were just too forced. The chips fell right and we had the right people in place to move smoothly into it.