When I coached youth football, one of my "practice before the game" routines was to do the traditional stuff like go over line-ups, remind the kids of special tendencies of the upcoming opponent, double-check who was going to be visiting grandma instead of coming to the game, etc. One part of that routine was to remind the kids of conduct and that they were representatives, not only of themselves and their team, but of their parents, school, faith, and community. Talked specifically about after-score activity, handing the ball to the ref rather than throwing it at them after plays, helping other players up including opponents, not saying anything to the other players other than positive comments, and if there was any problem, to tell a coach and the coach would talk to the ref or the other coach rather than them trying to handle it. I saw a person here on GID who has a tagline that says something to the effect that your are either coaching it or letting it happen. I like that idea in that both what we say/do and don't say/do has impact on our kids so, as coaches/parents, we need to be deliberate in that guidance from all angles.