Wayneburg,

I highly recommend going to the auto parts store and picking up some red and amber reflectors. They are extrememly bright (especially amber) and last forever. They might cost about $1 apiece.

The best way to get maximum reflectivity out of a reflector is to mount it so that it faces directly towards the source of light, namely car headlights. The less the angle of reflected light varies as the light travels from its source to the reflector and back to the driver's eyes, the brighter the reflector shines.