The second part of Acts deals a great amount with Paul's missionary journey. Chapter 15 is the council at Jerusalem; we then have Timothy joining in chapter 16-along with Paul in prison with Silas; chapter 17-21 accounts the visits to Thessalonica, Berea, Athens, Corinth, Ephesus, Macedonia and Greece, and Jerusalem. The end of Acts deals with Paul running from the authorities and being persecuted.
One of the verses that means a great amount to me, and many missionaries, is Acts 18: 9-10. For me it is beneficial to have this encouragement. It is so easy to just be silent, but to speak out takes courage. I think that this is a favorite quote when discussing missionary work, especially in countries that persecute those who are Christians.
I think that overall Acts is a good example for today's Christian society. So many times there are cliques and issues in the church that do not allow for true witnessing. In Acts, however, Paul traveled from city to city, faced persecution, and was still able to witness towards the end. I think that today's churches spend too much time inside the church instead of outside the church-where they are needed.