Make sure to use a good password, and change it fairly often. Password Tips
Do not open emails or email attachments if you do not recognize the sender.
Some viruses hijack a user’s email program and send out viruses, so even if you recognize the user, if the message or attachment look strange, verify with the sender that they intended to send you the file attachment before opening it.
Here is a list of several ways to make your computing more safe in general: General computer safety advice