So, being sent out by the Holy Spirit, they went down to Seleucia, and from there they sailed to Cyprus. And when they arrived in Salamis, they preached the word of God in the synagogues of the Jews. They also had John as their assistant.
Acts 13:4-5

One of the Paul and Barnabas’ common missionary methods was to go first to Jewish synagogues when entering a town. They did this for three reasons:

First, Jesus “came to His own,” the Jews (John 1:11). So the first missionaries went first to Jewish people as well.

Second, since Christianity was understood primarily as a sect of Judaism, going to a Jewish synagogue was a great place to begin in a new city.

Third, the Jews in the synagogues would have been at least somewhat conversant in the Old Testament scriptures, giving the missionaries a place to begin presenting Jesus. After all, the entire Old Testament is about Jesus (John 5:39-40).

Sadly, while Jewish people were often the first converts in a new place, there was usually great opposition to Christ and the gospel. As a result, after going to the synagogues, the missionaries would then preach Christ to Gentiles.

While missionaries in our day do not follow this pattern of going first to Jewish synagogues, missionaries still must prayerfully follow the Holy Spirit’s lead in how they enter each new place they go.