At Cape Air our part 135 pax briefings pretty much go as follows for the 402: there's three exits: door that you entered, right side of the aircraft and the crew door, keep your seatbelts fastened the entire flight (and operation of seatbelts), there's no smoking, fire extinguisher under the co-pilot's seat, floatation devices under all seats and briefing cards in the seatback pockets. Now of course all of these aren't suitable for part 91 flying, but it's probably a good place to start. And I left out the touchy-feely welcome aboard stuff and weather for the flight, though as a professional (or training to be one) it's certainly ok to add that stuff in .