Hours of glassing and studying the terrain and the target animal(s). Vast open areas are rarely pool table flat, therefore one can use the undulating ground to sneak closer. Go after single animals as they are far easier to get close to. The biggest stumbling block is getting upright, drawing and shooting your bow, that is when you get spotted 99% of the time. The other downside is that shots are usually at the very limit of most hunters, even experienced ones. A specially equipped bow and arrow set-up also helps a great deal, one that is purposefully set up to make such long range shots.