...
Eg ransomware could affect your backup also
How many backups do you need?
Eg I have at least 3
What needs to be removed from your backup?
Eg if you are deleting data for security reasons, then the data needs to be deleted from the backups also. This may result in needing to do another full backup. This can be a pain.
Data Destruction
Ensuring you deal with hard disks, computers, photocopiers, phones etc when they reach EOL.
Ensuring paper is securely destroyed.