You can file this one under the “obvious” category, but I figured this is worth a brief write up.

Whenever you use a public computer, be it at a coffee shop, library or wherever, do not ever go to a sensitive site such as your online banking. The reason is simple: since public computers are available for anyone to use, you don’t know who was using the machine before you and what they did. There is always the possibility malicious software, such as a keylogger, is installed on the machine and just waiting for you to visit your bank and capture your login information.

Keep in mind the machine available may not be properly locked down and may be open for anyone to install anything. Not visiting a sensitive site on a public computer – at all – is really the only 100% way to make sure you are safe from this type of theft.