Parking attendants are working for tips. So leave a tip when you drop off your car. Let the attendant know that there will be a second tip based upon the safe return of the vehicle. Also a positive attitude and a kind word goes a long way.
Make sure the attendant sees you recording your mileage. This will kill the urge to take your car for a joyride. Also be a little vague about when you will be back to retrieve your vehicle.
Most new cars come with a valet key from the manufacturer--use it. Put valuables out of sight. Most valet keys will not give the user access to the trunk and compartments. When you exit your car, remove your key from the ignition and place it in the attendant's hand. This will stop thieves who watch for unattended idling cars.
