Leadership isn't something people are born with, it's a developed trait. One of the classic examples of leadership development was done by none other than our Lord and Savior, Jesus Christ!
Apprentice selection; Jesus picked the people He wanted. His selection for apprenticeship was a relational process, and I think we would all agree those He chose weren't exactly what most would define as leadership material.
Apprentice expectation; Jesus designated them apostles! Apostle means "sent one." He was clear from the beginning that his expectation of these leaders in training was to go out on a mission.
Apprentice preparation; Jesus' disciples were with Him. They were mentored and given examples of life on life relationships. They were trained to saved the world by following in the footsteps of the example Jesus gave them.
Apprentice graduation; Jesus concluded their apprenticeship by sending them out to preach and have authority over demons. The apostles apprenticeship ended when they could do what Jesus did.
So a quick review. He sought his apprentices, defined their mission, had them learn His ways, and sent them out to do the task. Define, Learn, Do!