Ask HN: How do you encrypt your email?

In the wake of the PRISM stuff, I've decided to start encrypting all my email traffic. How do you do this? I'd really like to approach doing this in a secure and convenient manner that's easy enough for non technical people to get it (e.g. my parents). Obviously not every email I send needs to be encrypted, but I'd like to get in the practice of doing it right to ensure my privacy now and in the future.

Thanks!