When calling, pay utmost attention to wind direction and velocity. Coyotes will nearly always circle to the downwind side. Once they do, you will never see them again. A good steady (15mph or so) breeze is best because it 1) helps cover noise (like cocking your shotgun) and 2) your scent trail will be narrow. A vairable, shifting wind makes it difficult because your scent pattern may be as wide as 180 degrees.
Then again one night I was calling by myself (2 people back-to-back is best) sitting flat on my butt, peeking over some thick broomweed. I spotted his eyes about 100yds or so away. He had stopped and was sitting behind a small bush just watching. I switched calls (Burnham Bros mouth call) and he again became interested. I lost sight of him for a while and then all of a sudden he popped up over a small rise running full speed toward me. He started to circle to my right and I was having a hard time twisting around to the right while sitting with my shotgun shouldered. He broke through the weeds and I let go with #4 buck. I stood up a little shakey, took 8 steps and picked him up by his hind legs. I never weighed him but by the time I got home to show him to pops, my arm was hurting. Exciting stuff when you're 13.