"I wouldn't sit in the middle of the room, or an obvious place like a desk," he says.
"I'd sit on the floor with my back to the wall." "Both at home and on the road, you should put Post-its over your video cameras until you need to use them," Johnston says.
The i Message app on Apple products is quite good, he says, and so is Knox for Samsung devices.
The newest trend in social networking is the integration of video chat.
Video chat is now available on many smartphones and the social media powerhouses have introduced applications which make it easy to talk “face to face” with any of your social media contacts.
All speakers are also microphones, Johnston says, so your TV, radio and landline phone can all be tapped without an extra mic. "The water in the toilet bowl is not a bad acoustic resonator," Johnston says.
"So someone can tap into the plumbing and listen, to a certain extent." Even a glass held to the wall from the room next door can be effective, he says, especially if whoever is listening has thinned the wall.
Huma Abedin, Hillary Clinton’s longtime aide, left the former Secretary of State’s daily schedule on her bed in her unlocked hotel room during a conference - despite having a ‘burn bag’ for such items, according to recently released emails.