1. Learn the rules for your league and plan accordingly. Ensure that you have a league rule book. Do not assume that the league will follow the normal set of rules that you may observe on TV, as a matter of fact, many youth leagues do not keep score.
2. Make sure that you have all equipment that you may need to include extra balls, gloves, cones, whistles, etc... Inform parents of equipment that each player must have, particularly safety gear.
3. Coordinate with the recreation center or league on practice schedule to ensure that the field or court is free for use.
4. Do not let the parents sit on the sidelines. Enlist the help of other parents to assist in helping practices stay focused. The more adults you have on the field the easier it is to keep the attention of the players.
5. Break team into small groups for drills. Use other parents to run drills with smaller groups of players. This keeps the players out of lines waiting for their turn, it keeps them busy and engaged. Youtube has several examples of drills for all major sports.
6. Keep it simple. Do not focus on complex skills within the given sport. Instead focus on the fundamentals while teaching each position to every player. They will have a better overall understanding for the game if they decide to specialize in one position as they progress to other leagues.
7. Devise a rotation for players during games and stick to it. This is crucial to keep the peace among players and parents. Since most recreational leagues are not extremely competitive give all players equal playing time in multiple positions, stick with it even you are afraid that you may lose the game.
8. Most importantly have fun!