Public computers at libraries, Internet cafes, airports, and coffee shops are convenient, cheaper than buying your own laptop, and sometimes even free to use. But are they safe? Depends on how you use them.
1) Do not save your login information.
Always logout of any site you visit instead of closing the browser window or by typing in another address. This helps keep others from accessing your information.
Many programs (like instant messenger programs) have an automatic login feature that saves your username and password. Disable this option so no one logs in as you.
2) Do not leave the computer unattended with sensitive information on the screen.
If you have to leave the public computer for any length, logout of all programs and close all windows that may include sensitive information.
3) Erase your tracks.
When you are done using a public computer you should delete all the temporary files and your Internet history. Or better yet use the portable version of Firefox if you have a USB stick. ( http://www.johnhaller.com/jh/mozilla/portable_firefox/ )
4) Watch for people watching your screen.
People focus on how hackers can sneak into your personal files, we forget about the old fashioned version of snooping. When you are using a public computer, watch for people who collect your information by looking over your shoulder or watching as you enter sensitive passwords.
5) Do not enter sensitive information into a public computer.
You need to be careful that someone did not installed software on the public computer that will record every keystroke and email that information back to them. Then it does not really matter if you protected yourself because they still have access to your information. If you really want to be safe, avoid typing your credit card number or any other financial or otherwise sensitive information into a public computer.