Be sure to update your antivirus especially after returning from a vacation or when your computer hasn't been used for a while.
Antivirus software should be updated even before checking your email. Whenever your computer is shut down for more than 2-3 days, it's a good idea to let your antivirus software update itself before checking email or going online. The longer your computer is turned off, the bigger the risk. Don't rely exclusively on antivirus software
. It is far too easy to allow viruses and malware to enter your system. Try to stay with the mainstream websites which you can trust. Be cautious before downloading anything.
Even the best antivirus software cannot guarantee that your computer will never become infected. It is up to you to use caution when searching, downloading, or opening email.