If one of your soon-to-be-ex colleagues decides to do some damage before they leave the company, make sure that your work remains unaffected.
Have a checklist of all the accounts that they had access to. Don’t forget to remove their permissions when they leave.
Be careful of how you manage your passwords. Use strong and unique passwords, change them regularly, activate two-factor authentication and start using an app designed for password management.
Have multiple backups done automatically. This way, you won’t lose any of your important files or folders.