If you are doing a migration via import, complete the following checklist to make sure you've complete the migration fully:
1. Export data / connect systems
2. Clean source data or clean export
3. Define object mappings
4. Prepare destination fields on each object
5. Define field mappings
6. Prepare import files with object associations.
7. Run test import
8. Review imported test objects for correct field mappings, associations and engagement data