Practice judging distance. Over and under is very common. Second, if you are calling, be patient if you know they are around. Seems every year I stand up and watch them run away. I bought a decoy to try since I hunt alone, but I haven't had any luck with it yet. The idea of calling 20 - 30 yards from behind your shooter is probably the best idea, since most of the time the elk I have seen hold up have been less than 50 yards away, either out of site or just out of range.