Do not open any files attached to an email from an unknown or suspicious sender or any unknown files found on the Internet.
Do not download any files from strangers. Any files attached to an email unless you know what it is, even if it appears to come from a friend or someone you know. Some viruses can replicate themselves and spread through email. If the subject line is questionable or unexpected confirm that your friend really sent an attachment. If it looks like spam it probably is and should be deleted without being opened.
Delete chain emails and junk email. Do not forward or reply to any to them. These types of email are considered spam. If it is unsolicited then it is intrusive. They clog up inboxes and networks and by replying or forwarding them you are only adding to the problem. Also spammers use this method to harvest new email addresses. Don’t trust you and your friends emails with a stranger any more then you would your home address or phone number.
Exercise caution. When downloading files from the Internet ensure that the source is a legitimate and reputable one. Always have your antivirus turned on and updated. This will ensure that any file being downloaded is scanned with the latest virus definitions and help keep you safe.
Update your antivirus software regularly. Ensure that your antivirus and firewall are set to use automatic updates. Out of date security tools are almost like having no security at all.
Back up your files on a regular basis. If a virus destroys your files at least you can replace them with your back-up copy! System files can be replaced or restored but your personal pictures and documents usually can not. You should store your backup files in a separate location. Somewhere other than on your computer like a flash drive or CD.
Update everything regularly! Check with your product vendors for updates for your operating system, web browser, and email. One example is Microsoft Security Central and another is the Secunia Software Inspector.
Follow up on your suspicions. If you find a suspicious file on you computer you scan it with multiple antivirus scanners to determine if it is a threat or not. Use one or more of the following online file scanners.