It's a very hard problem IMO. Not just finding the words, but everything. For example, before learning linux to a degree where it wasn't a pain to use as a desktop, I thought it made no sense to waste time learning this or that security feature (like email encryption), because an expert would probably be able to fuck me anyway. Now that I have a better understanding, and I can mentally trace the information from end to end, know where it could be compromised, etc, I started caring, secured everything the best I could, and my friends now call me a paranoid (that didn't stop me from installing Thunderbird and Enigmail in their PC's).
So I think someone should explain to the people in a clear way that you don't need 100% security, but you need to understand when and where your information can get compromised, and what you can do about it. Eg:
- Private message on facebook - you are screwed
- Messenger - you are screwed
- Post on a blog - you are screwed, unless you posted anonymously and hidden your IP (which is not that easy, we know of many geeks who were caught even when they were using Thor, because they didn't fully understand the technology - hint: exit nodes)
- Email - you can encrypt it, and you are safe as long as both computers (sender's and receiver's) stay safe (assuming you store your private key there)
- Data on your computer - you are safe unless malware is installed, or someone gets physical access. You can use full disk encryption, but you will probably have to use Linux (personally, I use Ubuntu), so this is a far fetched goal for the regular Joe. There is also truecrypt for windows, but it's not full disk if I recall correctly.
- Etc.
I'll add a recent anecdote here: Just the other day a friend of mine replied to one of my emails, saying that gmail broke the encrypted email (meaning he couldn't read it, not that gmail decrytped it). In his reply, I received the broken email, and four emails from a private conversation he was having with other people. Something happened in gmail, something went wrong, and I got those emails. They came with headers and everything, he didn't copy/paste those (he wouldn't know how to do that). So there's another reason to encrypt emails: mails server can make mistakes apparently.