I just carry mine in my hand without any string to tie it on, it seems to work, but the controls on the ground are a problem to get to.
I tie mine with elastic to my wrist although for light pole O I used to carry it in my mouth since I needed the map board to lean on to write pole numbers. On the wrist seemed to work yesterday although I recall it sucked at Lake Monger. Need to thread it through the correct hole to get the numbers facing away from the wrist for easier punching.