You need to know how much your bullet is going to move with different wind speeds. Get that from ballistic software. Buy a meter and learn to recognize what various speeds of wind do to grass, trees, dust, mirage, etc. Make yourself some wind flags and see how they behave in different winds. Read your wind signs, estimate speed, correct accordingly. Ought to be simple, right?

Especially at longer ranges (like 700+), reading the wind is more witchcraft than science. Shoot something far enough away and the wind will be going four different directions between you and your target along with some vertical component. No go do it in winter when there are no leaves on the trees and grass is short and stiff. You may tire of primitive methods when nothing moves in winds from 0-10mph except the mirage.

Here's a link to the USMC sniping manual. There's a few tidbits in it that might help.

http://ofp.umbr.net/Other/milpubs/Sn...%201-3B%29.pdf