Cody Lundin and Scott Kozakiewicz recommend 10 feet of flagging tape for signaling. It flutters nicely in any breeze. I have some tied to a clamp-type paper clip. I clip it on a branch, near me, when I am coyote hunting. It lets other hunters know someone is there. It is helpful to see which way your scent is going.

It can also be used for a drip line, for your shelter, to keep the rain from following your cord into your shelter.