Many people don't think about backing up their data until something happens and they need to restore it. Don't be one of them: Back up your PST regularly, as often as once a day or once a week.
People who back up Outlook typically use Import and Export to back up their Outlook data or move it to a new computer. That's the wrong way to do it. Import and Export imports and exports only Outlook items; it doesn't touch custom forms, views, or other hidden items in the folders.