Based on situations we've encountered and various posts from the Learn administrators community:

• Please carefully consider how to implement legal name changes for individuals to avoid creating duplicate users.
• Always keep your regular integrations with the delete endpoint setting on Disable. Do not change it to Delete. It can happen that an integration is triggered with incorrect data, and if deletion is allowed, it could be a disaster.
  If you need to delete via integration, create a separate integration just for this purpose, and once you finish using it, switch the setting back to Disable to avoid unpleasant surprises.
• Add a password to each of your integrations. Remember that without it, anyone who knows the endpoint could act maliciously.
• Use different Data Sources
• Archive and save your upload files for at least some time. It’s easier to provide support if you can give the team the file used for the upload that caused the issue. Blackboard does not keep a copy of these files.
• Assume that at some point, someone will make a mistake and send an upload file that deactivates thousands of users, courses, or enrollments. Plan carefully how you intend to manage and fix the situation. (If you have the upload file, it’s much easier to undo.)
• Be consistent with separators and file formatting. This makes it easier to get it right the first time.
• Remember that usernames are case-insensitive while the external key is case-sensitive.
• "With great power comes great responsibility"... remember Peter Parker’s principle, and limit who has access to the integrations.

Inspired by a post from John Walthall in Community