Reflective tape is always a good investment. Put it around your flashlight, the inside of your car door that shows to traffic when opened, the inside of your trunk that shows when opened, and on tool boxes that you may use at a roadside. And around your bicycle helmet and on the fenders of your child's bike.
If you have a truck or vehicle with a bumper, it belongs on the bumper also.
Get a good quality tape. They can be a bit more expensive.
You can also make a reflector from a square of wood or metal fasced with this tape to mount from the rear of your car in the event you are stranded.