Rule #1 Never open links for banks, PayPal, e-Bay or an other of your accounts from an e-mail.
More often than not, the link is fraudulent and an attempt to get your personal information. It's better to launch a fresh browser and play it safe. Another trick is hitting reply and then running your mouse over the name of the person or business that sent you the e-mail. Often times, this reveals the bogus e-mail address.
Rule #2 Don't Get Sucked Into Stupid FaceBook questions requesting "harmless" personal information
I see these "questions" periodically on Facebook. List ten concerts you went to and one you didn't attend. Do you remember the first phone number you ever had. What was your first pets name? These all sound innocent enough but are often used by banks and financial institutions as challenge questions.
Generally, it's a good idea to clear your browsers cached information should you see any of these types of pop-up messages. Both Avast and AVG offer FREE virus protection that is as good as the paid versions available in most cases.