Establish a security policy in your organisation and educate your staff. If you're addressing this issue for the first time, start with these articles and adapt them for your needs. They know that security isn't guaranteed. For your computer system, backups are your insurance policy. If, despite all your precautions, something goes wrong, at least your precious data remains safe.
Backups mean the difference between a major inconvenience and a total disaster.
It takes time and effort, but you'll appreciate it if things ever go wrong. Take stock now to plan and write down your recovery strategy. Make sure you've got everything covered. As I said when we began, computer security is difficult, it complicates your life and it doesn't guarantee protection. But you still need it.