Rule # 1. The government monitors EVERY social media site, especially right-leaning ones (like FreeRepublic). So don’t post anything you wouldn’t say to an FBI agent’s face.
"Play your cards close to the vest." or "Loose lips sink ships." would seem to adequate advice.
Sucks to have to fear our own cops.
I have to respectfully disagree. Reason 1: you should never say anything to the FBI’s face. What you say will be used against you. Your innocent, law abiding statements will be twisted, misrepresented, taken out of context and used against you. Reason 2: if you don’t post anything because of the rule to not say anything to the FBI, then you abdicated your right to free speech. A right not exercised is a right lost. Silence does not make positive change.
Everyone should use their right to free speech to compel government to change. Freedom of speech should be exercised within the bounds of law. That means no threats of bodily injury or death. That means speaking truth and solutions.
Making threats of any sort in any environment is dumb and counterproductive as well as being illegal. It serves no useful purpose.
But faced with an FBI agent in person there are very few things you should say before consulting with your attorney. Some examples would be:
"Thanks for stopping by and giving me your business card. I'll ask my attorney to get in touch with you"
"Do you have a warrant? Can I see it, you can hold it up to the window" "You don't?" "Feel free to leave your business card on my doorstep if you would like me to ask my attorney to get in touch with you"
It may turn out that the FBI agent or other law enforcement officer has a perfectly good reason to want to speak with you, but that isn't always the case. The best approach is to be cordial and get your attorney involved before any conversation takes place.
You can read or see more detailed presentations on how to safely and properly interact with law enforcement officers in many places on the internet. Or you can ask your attorney.
Calm, cordial, respectful and keeping your mouth shut until you get your attorney involved is a good starting point.