One of the principles taught by the Positive Coaching Alliance (PCA) for defining sportsmanship is the ROOTS principle.  A pretty good baseline for coaches to establish expectations of young athletes. 

R is for Rules
Rules keep the game fair. If we you play or win by ignoring the rules, what is the reali value of your victory?

O is for Opponents
Without an opponent, there would be no competition. You need to honor strong opponents because they challenge you to do your best. As an athletes you can be both fierce and friendly during the game; playing hard to score or make an out is compatiable with being friendly and helping an opponent up. Coaches showing respect for the opposing coaches and players sets the tone for the team and the game.

O is for Officials
Respecting officials, even when we disagree with their calls, is probably the hardest part. Officials aren't perfect just like coaches, athletes and parents, we all make mistakes.  As a coach it's important to think about how to best approach an official when you want to discuss a call. It's important to keep a level head and remember the young eyes watching you.

T is for Teammates
Athletes must understand that being part of a team requires thinking about and respecting one"s teammates. This respect should carry beyond the sport and into the classroom and social settings. Athletes should also realize that their effort in the game also reflects on their team. Respect is critical and reflects back on the team in all situations.

S is for Self
Athletes should live up to their own highest personal standard of Honoring the Game, even if their opponents do not. Athletes" respect for themselves and their own standards must come first.

You can read more about honoring the game at www.positivecoaching.org