I did four years of umpiring little league, Pony league, some high school and some Mens Amateur in Dallas before coming here
Main requirement is to decide right up front that every criticism other than from your colleagues is motivated by huge self-interest and therefore *Anything* you hear needs to be shrugged off.....and best when done with a no-words smile
Also helps if there is any kind of short (60-90 seconds?) pregame w both head coaches to patiently reset core ground rules on behavior. In baseball the main point we hammered was "I will respectfully listen to most any complaint you have but if you start any arguments about balls&strikes you are gone"
Solid advice.