EFF has released an important guide on protecting your privacy. From the press release:
The Electronic Frontier Foundation (EFF) launched its Surveillance Self-Defense project today — an online how-to guide for protecting your private data against government spying. You can find the project at http://ssd.eff.org.
EFF created the Surveillance Self-Defense site to educate Americans about the law and technology of communications surveillance and computer searches and seizures, and to provide the information and tools necessary to keep their private data out of the government’s hands. The guide includes tips on assessing the security risks to your personal computer files and communications, strategies for interacting with law enforcement, and articles on specific defensive technologies such as encryption that can help protect the privacy of your data. […]
Surveillance Self-Defense details what the government can legally do to spy on your computer data and communications, and what you can legally do to protect yourself against such spying. It addresses how to protect not only the data stored on your computer, but also the data you communicate over the phone or the Internet and data about your communications that are stored by third party service providers.