Check for enabled but untrusted constraints.

Log performance/error/etc information to a monitoring server

Log security information to a monitoring server

Log backup/agent job/error log information to a monitoring server

Optional: Restore a database backup as a test

- if you don't do this, at minimum backup with CHECKSUM and then RESTORE VERIFYONLY, but that's still not as good as a real restore.

Optional: check for disabled constraints.