One of the most important things as being a volleyball coach, your players should be comfortable around you. If you make them uneasy, than maybe you shouldn't be coaching. Also, depending on how close you are to the team is how open the players will be. When a player can talk to you about anything and loves coming to volleyball because you make them comfortable, you're probably one of the best coaches out there.
However, there aren't too many good coaches out there and once you find a philosophy that works, try to stick with it as long as you can. Although, you need to treat different age groups different ways though or there may be some problems with the parents. Youth volleyball coaching techniques will vary greatly from a high school coach to a recreation youth league coach (who is probably volunteering). The younger the players are, the more you have to be their coach and their friend.
Even if you can't be as open with the younger kids, youth volleyball coaching techniques are a lot easier to deal with. Usually when they're young, they just try to get the ball over the net to anyone they can. Therefore, you won't have to do volleyball blocking drills or libero volleyball training which makes it a lot easier on you as a coach! Regardless of the age group you coach, as long as you stick to a plan you'll be sure to get rave reviews as a coach!