OK, here comes the important pages.
Besides playing for fun, you should play to win - using only fair play (as your group happens to define that)
I assume that you are playing a campaign and not a single game. When playing a single game, there are no reason to try to keep the band intact, so in these games 95% dead bandmembers can still count as a wictory. Not so in a campaigngame.
It is my belief that the most important issue is to keep the band alive and usefull. Any game that your band participate in that leaves you with losses that you can't buy back at once, are a lost fight.
If a hero that had gained some experience and usefull increases died, the fight was a substancial defeat.
If only henchmen died but was not bought back (give or take a model), the fight was a minor defeat.
A major victory is a fight that result in no losses on your side, some experience for your heroes (henchmen and hired swords are usefull but don't count here), something usefull found during exploration and lots of gold. If your opponent happens to qualify for a substancial loss, then you have won dessisively