While the original article was one geared towards a person with top security clearance, these are good things to at least be aware of in everyday communications.
Completely avoid using any government-owned computer or network for web surfing. Use only privately owned computers and non-DOD/non-government networks.
Use The Onion Router (Tor) for all of your web browsing. If you are not familiar with Tor, then get up to speed quickly.
Use anonymous re-mailers for any e-mails that say anything more than: “I miss you and I can’t wait to get home from this deployment.”
Use an inexpensive VPN service.
Be very careful about how you phrase your e-mails, even if they go through a re-mailer and use strong encryption. Warn all of your friends and relatives to do likewise in their e-mails to you. (Since the contents of incoming e-mails can be nearly as damning as outgoing e-mails, in the eyes of investigators.)
Rather than copying and pasting the text of anything controversial from any web site, instead send just Permalink URLs, couched with statements like: “I haven’t had the chance to read this yet, but Bob said it was worth reading” (or some such.) This will provide plausible deniability.
If you buy any books that might be deemed controversial then buy only hard copies, pay cash, and don’t leave a paper trail. I would suggest gun shows, preparedness expos, and “brick and mortar” bookstores are the best places to buy such books. If you are deployed overseas, then have your relatives buy books for you and ask them to send them to you in Flat Rate boxes.
Don’t consider ANYTHING you do over the Internet to be “secure”, even if you use strong encryption.
Get in the habit of sending traditional typed or hand-written letters. If you are worried about the receiver of the letter being under surveillance (a warrantless Postal Mail Cover), then put their address in both the TO and FROM blocks on the envelope.
full article here: Single Scope Tyranny – SurvivalBlog.com