I have an inclinometer/level on the front of my scope. I pull the target string over the level and hold it in my left hand while in position. This puts the string so my left eye can look down it as I get ready to shoot. As I break the trigger I let go of the string. It takes a lot of practice before it becomes easy.
The first time you look down the string and see it bowed into an S shape... you will understand the value of its information.
The beauty of the string is that it doesn't care about the angle that the wind is blowing. There is no angular math needed to calculate drift. The amount of bow in the string directly correlates to the hold distance because the string bow is vectored the same as your pellet. A 45 degree angle of the wind will push the string bow about 70% as far as the same velocity that is at 90 degrees. Same as a pellet.
Mike