Prevention is better than an often costly recovery (or no recovery at all)!
If we had to give only a single bit of advice, then, based on current crime reporting, it would be this: Do not give sensitive or personal information to anyone unless you are sure that they are indeed who they claim to be and that they should have access to the information. Moreover, you cannot be sure of the identity of someone who sends you an unsolicited email.
General Cyber Security Tips
This will take you to information maintained by the United States Computer Emergency Readiness Team. It contains non-technical descriptions and advice about most common computer security issues.
Identity Theft Prevention
This will take you to a page maintained by the Federal Trade Commission on identity theft, privacy and security.
Be Crime Smart
This will take you to the FBI's crime prevention page. It deals with a variety of crimes including those relating to children, the Internet, and other computer-related crimes, frauds and scams.