Please encrypt your communications whenever it's possible. Not because you have something to hide, but because there are many entities handling our private data that do not necessarily have their interests aligned with our personal privacy (probably an understatement).

For text messaging (Android only) I use the excellent 'TextSecure' app, which is an open source drop-in replacement for the standard messaging app on your phone. You can read more about it at http://www.whispersystems.org/

The aforementioned Whisper Systems also has an app called 'RedPhone' for secure voice, but I have yet to try it. If anyone uses it, I would be very glad to hear your opinion.