From the list below (see "Christian Advent") there is a ready-made outline for the four Sundays of Advent.
On the first Sunday, the church can focus on the Christian concepts at the manger (peace, love, joy and hope) and what those mean to us in the form of Christian education and implementation of that knowledge.
On the second Sunday, the church can focus on the animals at the manger (donkey, cow, sheep, and camels) and their attitude of uncomplaining service and how we as Christians should imitate their humble service to God.
On the third Sunday, the church can focus on the people at the manger (shepherds, wise men, angels and Mary & Joseph) and how they worshipped a new-born baby and only Mary really, really knew the full story (Joseph had to trust Mary). How does the church today really, really worship God and is it worthy of Him?
On the fourth Sunday, the church can focus on the cities of the Christmas story (Nazareth, Jerusalem, Bethlehem and Babylon [where the Magi came from]) and how the church using evangelism and fellowship to reach out to those people who do not know the Christ story.
Each Sunday, one part of the mission of the church, one part of the Christmas story. There are so many aspects to this concept that ministers have a wealth of material. But please, keep it simple - God's revelation through Jesus is not complicated but it difficult. Don't try to make the Christ-story easy and complicated.