I'll go against the grain here and say that good basic hunting practices are far more important than the brand of call you're blowing. Scout, scout and scout some more. Use camo that matches your terrain. When approaching a stand, slip in quietly and try to remain unseen. Watch the wind and if nothing responds, then try to exit quietly and unseen.
Every body calls differently, there is no one right way to call. I call very little because I hunt alone a lot. I feel that the coyotes come in slower and look more for the source of the sound. A buddy gets on the call and blows almost non-stop. I keep thinking he's going to blow a lung, but we both call coyotes. I have taken out guys that are new to the sport and laugh at their inept calling until a coyote shows up and I'm not ready. I have called coyotes with a piglet in distress tape where there isn't a hog farm with in a hundred miles. It's the sound of an animal in distress and that's what matters.
Any predator call will call predators on any given day. I feel it's more important to play them a tune they haven't heard before. I tell new guys to go to all your local sporting goods stores and see what is available in your area. Then get on the internet or check the catalogs and buy something that isn't available in your area. There are a lot of callers in my area and I think that with in 30 miles of town, any coyote over a year old can tell you the make, model and year of manufacture of just about any call you blow.
Sorry for the long winded response, but I hope this helps. Dale