my suggestion would be get with someone who has done it well and on a regular basis.
My neighbor was on a National Guard/Army team that went to the big shoots. He did some of that 900 meter off hand shooting. He even has an article where, at the Canadian Nationals or something like that, he out shot the legendary Lones Wigger.
We hunt coyotes together behind the house. He humbles me a bunch. For instance, 3 yotes take off at the same time. While I'm trying to figure out which one to shoot at, he has the 250 yarder dead in its tracks. His most notorious shots was precisely up the vent @ 70 yds w/a 40gr VMax in a Hornet. Both the bullet performance and his shooting was impressive.
I do notice that all of his carry rifles, for yotes, are Rugers from 22LR, 222 and 223 all feel the same to me. Must be something to that.
The difference between he and I, besides a bunch of experience, is that while I take just a portion of a second to think about some kind of a rest, he bags the yote.
I've learned from him that the most important aspect of off hand shooting is the trigger pull. Even if the rifle is waving around like a flag in the wind, well at least not steady, if the trigger pull is right the bullet amazingly goes where it should, most times.
I may be the slowest guy on the mountain . . . . but . . . . I'm on the mountain!