I recently had received a scrap piece of Scotchlite sign making material in white, and thougt of a use for it on my helmet. First cutting it into 3/16" strips and applying it to my helmet at various locations. It's nice since it doesn't contrast with my silver helmet, but they offer several other colore, including black which reflects back a golden color when hit by the headlights.
1st pic: starting in the front, center and worked around the sides along the bottom edge.
2nd pic: side view with the reflective stuff along the edge of the visor.
3rd pic: rear shot
Stay visible, people!
Steve F