Many people complain about issues with their privacy, much to do with information being stored when browsing to when using a social network. Part of why we are able to access so many sites freely is due to the fact that they can take our information.
To a certain extent this is okay as long as we are aware of what they are taking and to whom they are giving that information to, which you can check easily through PrivacyFix (another plugin), however, revoking such info does not give them another alternative to provide you with a free service, which causes an unbalanced medium.
Thus, using another option by blocking your information from being retrieved by using a Firefox plugin known as NoScript, this plugin will run only trusted content and protect you against XSS and Clickjacking attacks.
However, many reviews state that this plugin is best suited for those who are more computer savvy, but I say, you be the judge.