My stalking mentor got me to tie a length of fluffed up cotton to my stalking sticks, that way you always have a visual indicator as you walk along. Works great even when the sticks are deployed and you are waiting quietly in ambush.
Piece of cotton tied on the sling or bipod
simples pick some grass throw it up and whoosh away with the wind,
but mind sometimes the wind direction can be misleading
if your in a ride
or on the brow of a hill
or in a valley
any where it can be channelled
only on open hill will the wind be uninterrupted and you will get an accurate direction
I am a smoker so its easy for me, but the talcum powder as mentioned works as does the little bottle and ring for blowing bubbles
that kids have.
I live next to the biggest wind farm in europe so i look at the mills.
talc, pieces of cotton, grass and whatever else you think of only tells you what the wind is doing were you're standing. Not uncommon for wind to shift, change direction 180 degrees and change magnitude - especially out on the hill.
Observe the vegetation out to your intended target - watch it in increments out.
I always have some small feathers in my pocket
The powder is really good when the wind is too light so move the grass or feel on your face, it will show a wind which is to light for a piece of cotton but still strong enough to ruin a stalk.Also the hairs on the back of your neck will often alert you to a wind which has moved behind you. I stalk in one valley where the wind blows straight up from behind when you start to stalk it, which would make you think it was useless to stalk, but I know from experience that in 200 M it will veer 90 degrees and blow straight up the hill to one side and leave the rest of the valley free to stalk.