Cleaning bad data after GDPR

Hi guys,

We are about to hire a intern to help us with some data cleansing task. However after GDPR I just want to make sure this is done  in compliance with data protection and also don't want our intern to get into troublers. Can you recommend any best practices to do this for EMEA DB ?

Type of task that this person will be doing are: Country names, Phone number append (Int Code), Job Titles, etc etc..  Common temptation that will come up is fixing  (joe.doe@gmal )

Any ideas will be highly appreciated.

Diego