4. Pay attention to the risks of e-mail. 

Think twice before you open attachments or click links in e-mail—even if you know the sender—as these can be used to transmit spam and viruses to your computer. Never respond to e-mail asking you to provide personal information, especially your account number or password, even if it seems to be from a business you trust. Reputable businesses will not ask you for this information in e-mail.