As the book of Acts charts the growth of the early church, it tells the story that we are part of today. Jesus commissioned his followers to be his witnesses to the ends of the earth, and he empowered them with his Spirit for the task. He have the same Spirit and the same mission, and many of the challenges experienced by those first believers are the same challenges that we face today. Acts serves a dual purpose of being a blueprint for how things can be for the church, and also a gritty description of the reality of living out the mission. Both are profoundly helpful for the church in its mission today.
This is a fairly lengthy preaching series that goes through the whole book of Acts. You could preach through the entire series in one go, or if you prefer you could break it into sections and do some other series in between (the end of chapter 8 is a good place to break the series up).