@Rodrigo_Mohr you need to mainly consider below things
1. Number of managed tables
2. Number of external tables
in case external tables upgrade tool will help which is built in with UC, where as for managed you need to either go CTAS/Deep clone. but we do have limitations like while migrating external tables it will show which tables can be directly upgraded to UC.
you need to move out form mounts to external locations and that should handle external table upgrades
once after upgrading you can govern users based on new access that UC supports