Help the boys to understand that true leadership is first and foremost about setting a good example for others to follow.  If you ask which of your players have ever done something bad and had someone else follow them doing the same bad thing most of players will raise their hand.  Then ask them if they have ever done something good and had someone follow them doing the same good thing.

Help them understand that by their example they will be a good or bad leader.  It's up to them.

Other characteristics of a good leader are: 

• looking out for people who need help and then helping them without having to be told to do it,
• protecting people who are weak and not able to defend themselves,
• having the courage to do the right thing when no one else is willing,
• seeing things that need to be done and taking the initiative to get them done

 
On the basketball court examples of a good leader are:

• players who stay focused and listen to the coach during practice,
• players who help teammates when they see a player that doesn't understand what to do,
• players who during the game make sure everyone knows who they are guarding
• players who work hard in every practice and prepare to do their best in every game.