One of the most simplest technique which i often use is key logger.
These are the following steps you need to do with key logger :-
1. Download it from here. Want to download free key logger.
2. Install its setup to public libraries, cyber cafes, your friend computer or your office computer.
3. Hide it after mentioning your email id into this software.
4. Check your email, you start getting user name and password of everybody who use that computer. And their is very basic thing about user name and password. People often have same password for all the services they used.