The best defence, is a good offense. Be proactive with proper maintenance.
Your first and best defense is to have an antivirus program and to keep it current with all the latest updates. Many new machines come with an antivirus program, but sometimes they only include a few months of updates, so be sure that yours is up to date. An outdated antivirus program isn’t much better than none at all.
In general, Windows users should turn off file and print sharing. Most people have shared folders/directories without realizing it, theoretically allowing anyone on the internet to add or remove files from their computers. Computers with Windows XP, for example, have a “Shared Documents” folder that is freely accessible to other computers. Because NetBIOS can run over TCP/IP (NetBT), sharing a folder or printer makes it avilable to anyone on the internet unless your ISP helps you out by filtering NetBIOS traffic.
Some hacker groups run port scanner programs looking for systems with File and Print Sharing enabled and post these IP addresses to public sites. Protect yourself by un-sharing shared folders on your computer and by disabling File and Printer Sharing in your network settings.
These procedures vary by operating system, so consult your computer’s documentation or search the internet for more specific instructions.
* Install and Configure AntiVirus Software with Daily Updates. One of the best defenses against viruses, worms, and Trojans is using a desktop anti-virus software with automatic updates. You will find links to many popular antivirus software in the
Links & Downloads area.
* Make sure that you download and install critical updates on your computer. Microsoft periodically issues patches to Windows to make the operating system more reliable or secure. Windows has a built-in facility called Windows Update that downloads and installs critical and security patches to keep your system safe from attackers. Configure Windows XP to automatically download and install critical updates
* Windows users should familiarize themselves with the security resources provided for them by Microsoft located at http://www.microsoft.com/security.
* Do not click on links and download games from unknown, unreliable websites. Many times, hackers create trojans, programs disguised as games, especially children's games, but are actually doing malicious things in the background. Don't forget, hackers will do anything to get their malicious code on your system.
You should also scan removable media (floppy disks, zip disks, CD-R’s, etc.) that may have been used in other computers to be sure that none have been infected.
* Never open files or file attachments in an email from unknown sources, or if the subject line is questionable or unexpected. If there is an attachment that you are not specifically expecting, never open it, even if it appears to come from a friend or someone you know. There are some viruses that have the ability to replicate and spread through email. If you get something unexpected, contact your friend to confirm they really did send it to you. In some instances, if their email account was hacked, they may never have knowingly sent it to you.
* Immediately delete all chain E-Mail and junk E-Mail. Never forward or reply to them. At best, these E-Mails are spam, clogging inboxes, and the Internet in general. At worst, you could be spreading around a virus.
* Never download files from strangers or people you don't know, or sources you don't know are legitimate.
* Back up your computer regularly, storing your backup not only on your computer, but also on an external hard drive, possibly a large USB flash drive, but also keep a copy in a separate location, not on your computer.
An excellent option is the cloud based DropBox.com, however you would definitely want to encrypt your data first before putting it on a cloud based service like this.