OoJesusoO

Lets say you don't give out any information about your RL what so ever when you talk to others inworld nor post any information leading to your Facebook/twitter pages and you don't give any information in your RL section of your profile neither. Basically, what happens IRL stays IRL and your identity is a mystery. So, my question is are there some ways creepers may try to access this information or mistakes others make leading to having their information out in public such as where the live? If so, what are they and how can you prevent it?