When it comes to security, who do you trust?

Security involves both hard ware and software but the major piece of protection is software used to encrypt communications or to make your identity secret or otherwise facilitate a private communication with others.

The first rule of thumb, if you are considering software security options do not use or trust those from BIG companies or that do not reveal their source code.  You have no way to know if there are back doors or if those providers have secret agreements with others to provide your information or keys to decrypt your communications.

Companies like Microsoft, Facebook, Intel, McAfee, Symantic Google, Skype ( part of Microsoft ), etc. all have contracts or agreements with intelligence services.  All of these claim your communications are encrypted, they are, however they hold the keys to that encryption and are able to decrypt anything they choose or pass those keys on the agencies like the NSA, CIA, FBI and others.

Rely on open source software only. These are developed by programmers who work with others and freely publish the source code to their programs which means it can be scrutinized for any deception or hidden back doors to their encryption.  Strange as it may seem, one of these means of anonymous communications, TOR, was developed by our own government in order to create secure methods of communication between military personnel as well as foreign dissidents trying to over thow hostile governments.  It was created in such a way that not even our own NSA can track people using this network.  Note that TOR does not necessarily assure privacy, it's first duty is anonymity.  You still need to assure that your communications remain encrypted beyond the TOR network and this is where other methods designed to assure privacy are use in conjunction with anonymizing networks.

True security comes with end-to-end security in which the entire communication remains encrypted until the intended recipient, using a unique key, decodes what you have sent.

There is a very good article about privacy and anonymity offered by and for journalists. It is available online and as a PDF download HERE.

You will find more information about securing emails HERE.

If you choose to use real time chat or IM, do not use the clients offered by the service providers. Do not chat via Yahoo Messenger, ICQ, AIM etc. unless you install an open source chat client that can provide end-to-end encryption.  This is Pidgin and it will allow you to consolidate all of your chats into one client and then encrypt the contents.  It is also necessary that your chat partner have this installed on their computer as this must be done between two clients with encryption installed.

Bottom line...don't assume the big software companies are doing a good job protecting your privacy. Their goal in life is to make money and one way they do that is to trade or sell your information.

By the way, many of the security methods are available for use on your smart phone as well, most notably on Android considering that Apple's iOS is proprietary and anything you do on your phone can be known by the operating system.  iPhones should not be considered a good choice if security and privacy are important to you.