Watch out for emails posing as something they are not.
One of the last scams on the Internet are emails posing to be sent by a large company. These emails try to trick you into disclosing banking and credit card information by requesting an update to their records.
No legitimate company would ever request sensitive or private information via email.
Knowing this, some of these scams are getting trickier by giving you a link to a web page with a form to fill out. Once again, never give out any private information without verifying who will get it.
Let's say the web address of the link is ebay.update.com. While it does look like a good "ebay" address, it is NOT part of ebay's website. So, be very careful.
Just as you would never give any sensitive information to some that calls you (because you can't verify who they are), don't do the same with emails either.