1. Install anti-virus software. Many options are available in local retail stores, and online. Users that have a reliable, persistent connection to the Internet may wish to consider products from vendors such as Trend Micro which update themselves automatically at regular intervals to optimize virus protection while reducing manual maintenance tasks (these types of products often have an annual fee associated with them, but some are free for qualifying users).

2. Update virus definition files regularly. Hundreds of viruses are discovered each month, so you'll want to be protected.  These updates should include at a minimum the product's virus signature files.  You may also need to update the product's scanning engine as well. 

3. Do not open any files attached to an email from an unknown, suspicious or untrustworthy source. Do not open any files attached to an email unless you know what it is, even if it appears to come from a dear friend or someone you know. Some viruses can replicate themselves and spread through email. Better be safe than sorry and confirm that they really sent it.

4. Do not open any files attached to an email if the subject line is questionable or unexpected. If the need to do so is there always save the file to your hard drive before doing so.

5A. Be aware of and delete (don't forward) virus hoax emails.  What's a virus hoax email?  A virus hoax email is an email that tells you about a file on your system that you need to delete ASAP, the email claims the file is a file related to a known virus.  Problem is that these virus hoax emails usually tell you to delete a file that your operating system or other popular software requires to run properly.  Next time you go to start up your computer or fire up your favorite application you could find that it will not run, and all because you deleted a virus-free file!  Read on... 

5B. Delete (don't forward) chain emails and junk email. Do not forward or reply to any to them. These types of email are considered spam, which is unsolicited, intrusive mail that clogs up the network.

6. Do not download any files from strangers. 

7. Exercise caution when downloading files from the Internet. Ensure that the source is a legitimate and reputable one. Verify that an anti-virus program checks the files on the download site. If you're uncertain, don't download the file at all or download the file to a floppy and test it with your own anti-virus software. 

8. 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. You should store your backup copy in a separate location from your work files, one that is preferably not on your computer. 

9. When in doubt, always err on the side of caution and do not open, download, or execute any files or email attachments. Not executing is the more important of these caveats

10. Keep e-mail clients updated. Asking users to apply the latest security patches (if applicable) to their respective email clients may also reduce the risk of virus infections in your office. We are aware of multiple patches for Microsoft Outlook in particular.

11. Keep web browser(s)/operating systems updated. Updates and patches for browsers/operating systems resolve known security holes that, when left open, can allow lead to exploits of the security holes. In theory, these exploits could lead to viruses being passed to a system.

12. Alert users to contact the system administrator when viruses are found. Usually when an anti-virus application finds a virus it will prompt the user. The user has the option to take a variety of actions. We recommend that users contact the system administrator when viruses are detected so that the administrator may take appropriate action.

13. Do not allow foreign computers to connect to your network, unless they are clean of viruses. Make certain that any computers connected to the network are running AV software, are properly configured, and are using the latest virus definition files. Viruses can travel over the network to open network shares.

14. Consider a global anti-virus scanning application. There are applications that scan all incoming TCP/IP packets for virus strings. These applications act much like a firewall, but trap viruses rather than unwanted port connections. These applications usually run between a firewall/WAN and the proxy server/LAN.