 Walking groups, if possible, staying well in areas, using normal travel routes, which people usually walk. Make sure they got your cell phone with them, everybody has one nowadays. Keep it fully charged. If they do get approached by somebody like that, just keep walking, don't stop, try to get all the information they can on the vehicle, color, description, tag number, that way we would have a chance of locating who it is and maybe get a chance to talk to them about the incident.