It is important that you determine what you want to accomplish with your team before you put the team together. This will set expectations for you and your team and will help you establish goals that meet those expectations.
When we first started helping out with the puppet team that was already established, the team met on Wednesday nights after mission activities like R.A.s and G.A.s. It's purpose was to provide another activity for kids to go to on Wednesday night while their parents were in choir. As such, it had no goals beyond what needed to be accomplished each Wednesday night. They would occasionally perform songs in doorways during Sunday School as well. This is fine if that's what your ministry is intended to accomplish.
We established our ministry specifically to give kids a place to experience being a servant. The hope was to instill in them the desire to serve in leadership roles when they got older.
Here are some of the questions you need to answer when creating your mission statement.