I agree with all the steps SueTons, except after a role switch, jobs that ran on the former principal database must be disabled and recreated on the new principal server(DR) to run there(if needed) and the logins of users or processes that need to connect to the database should be created in Mirror(Fix Orphaned users). When the former primary/principal server instance is available after testing, you should delete/disable the original jobs in DR.

You will need a log backup from Prod to reconfigure mirroring. These are my assumptions