1. Setup your email and any other accounts with two-factor authentication whenever it is available. This must be done beforehand. Gmail, PayPal and eBay are three online services that offer two-factor authentication. There are many others.
2. If you can't or don't use two-factor authentication, you must assume that whatever username/password you type on the public computer will be recorded. For this reason, it is critical that you change the password on all of those accounts as soon as you have access to a secure computer. You should also monitor those accounts for suspicious activity and report any violations immediately. - DF
Editor's Note: Simply put, two-factor authentication is an approach to authentication requiring two different confirmations that someone is who they say they are. This lessens the ability of the hacker to get into your account.