There are several things that go into making a successful troop. You start with a good mix of scouts, from older to younger. You need well trained Senior Patrol Leader, and Patrol Leaders. You need trained adult leaders (Scout Master, and Assistants) to oversee meetings and events. Last you need a full committee to make sure the Scouts have what they need.
Lets start with the scouts. It is important to have a mix of older and younger scouts. The troop is run by the boys, so the older boys train the younger boys how to work together. The older boys and boy leaders set the level of expectation and then they hold the younger boys accountable to meet that expectation. If they are given good direction they will meet the expectation every time.
The leaders are the next important ingredient. They are the adult supervision for the meetings and events. They guide the senior patrol leader and the patrol leaders. They take care of the administrative parts of the camp-outs. They ensure the boy leaders plans move the younger boys in the right direction.
Last is the committee. This can be one of the most important parts of a successful troop. They are responsible for making sure the adult leaders meet the requirements for their position. They have to ensure the troop has all of the equipment it needs to run. It is their responsibility to make sure the troop stays in the views of the charted organization. They are responsible for the administration of the troop. The committee should be all of the parents that are not adult leaders.
If the troop has all of the above ingredients then they will have a successful program.