glad you asked!
most of the unwritten rules are just plain commen sense and consideration for the other team. Here's a few:
-no throwing paint by handfulls at the other team. Not good sportsmanship
-no asking refs where the other team is. teams need to work togeather to establish where the other team is, not by cheating with refs(not THAT way) lol
-No bunkering newbs. Most experienced, sick-minded, or both types of players like to bunker players(i'm a front man; I bunker and I like it), but only the latter like to shoot up 12 yr olds. You just don't bunker(without asking for a surrender) anyone young or inexperienced.
-Sharing paint with teammates is fine 99% of the time. The other 1% is when you have to leave the field to get it
-Play nice! Don't play malisciously, trying to intentionally hurt someone else. People don't pay $10 to get shot 5 times in the throat. once is enough
Basically, just use common courtesy and the grandma rule.
what, u don't know the grandma rule? The granny rule is: Would your grandma pimp slap you if she saw you do that to that 10 yr old?
-Petey