You saw some interesting precautions in the movie "Casino": Talking at bus stops with mouths masked; talking "personal" stuff for X number of minutes until the FBI was required to hang up; having cars stashed away at indoor garages and changing them in the course of a single trip, etc. But, the best precaution is to talk one on one outdoors while walking, heads down. Joe Massino ordered all his family's social clubs closed as a precaution.