• Use common sense: If you're unsure about an attachment, delete it. Especially if it's from a source you don't recognize.
• Scan files for viruses before using them: Especially, if you are using a disc or flash memory (pen drives, thumb drives, etc.) to carry information between one computer and another. You could easily pick up a virus from a corrupted file and introduce it into your system. Running a virus scan before launching any of new files will prevent infection.
• Don't share data CDs: Even a well-meaning friend may unknowingly pass along a virus, Trojan horse, or worm.
• Don't boot from an unknown data CD: Data CDs are one of the most common ways viruses are transmitted. If you are using a data CD while working on your computer, remove it when you shut the machine off or the computer may automatically try to boot from the disc, perhaps launching or installing bad programs or files on your computer.
• Don't download programs from the Web: Unreliable sources such as Internet newsgroups or Web sites that you haven't heard of may be willing providers of viruses for your computer. If you do have to download from the Internet, be sure to scan each program before running it. Save all downloads to one folder, then run virus checks on everything in the folder before using it.
• Update your anti-virus software frequently: An anti-virus program is only as good as the frequency with which it is updated. New viruses, worms, and Trojan horses are born daily, and variations of them can slip by software that is not current.
• Get immediate protection: Configure your anti-virus software to boot automatically on start-up and run at all times. This will provide you back-up protection in case you forget to scan an attachment, or decide not to.
• Scan all incoming email attachments: Be sure to run each attachment you plan to open through the anti-virus check. Do this even if you recognize and trust the sender; malicious code, like Trojan horses, can slip into your system by appearing to be from a friendly source.
• Don't open attachments automatically: Be sure your email program doesn't automatically download attachments.
• Install reliable anti-virus software: Anti-virus software scans files regularly for unusual changes in file size, programs that match the software's database of known viruses, suspicious email attachments, and other warning signs. Norton Antivirus is the world's leading anti-virus software. It runs continuously in the background of your computer, providing constant protection from viruses, Trojan horses, worms, and other malicious code. To stay up to date on the latest online threats, Norton Antivirus automatically updates its virus definitions whenever you're online.

These precautionary measures may seem to take time and some may feel that they are going into over-kill. However, for those who have had viruses, they will seem like rational precautions.