Please refer to Fellowship of Prayer Strategists for prayer strategies for field workers and intercessors; many of the same strategies apply. Here are a few specific ideas related particularly to diaspora.
Repent of past and ongoing sins regarding migration, including those committed against indigenous peoples, trafficked peoples and exploited workers.
Strategic locations for prayer may include transportation hubs, cultural centers, schools, etc.
Praying with children and youth about the movement of people
Pray for more people to engage and partner together
Pray for humility and willingness to obey, even to the point of death. Attitudes of doing what is convenient must be replaced by radical obedience.
Pray for relationships to develop with healthy, mutual respect. Hospitality, generosity and teaching should go in both directions.
Pray for grace to cover misunderstandings and remove unintended offenses. It may not be possible to be all things to all people at the exact same time.