I use a howl from an open reed call, but rarely need to do so. I hunt the same area and I know where they tend to be. I hunt mostly at night, so I usually wait until they start then I join in. Barks and yips should get them curious enough to investigate. Too much and they'll figure out that its not a coyote......if they respond with what I can best describe as "chattering" along with barking and yipping....sadly, you've been busted and they are warning the others. Be careful not to give a warning to them too. However it can be intertaining to imitate the coyote every time they give a warning, they get riled up and irritated, but they most likely won't show themselves.
If you know their routes and you hear them close by you can stay hidden and at times shoot them without calling.
Advanced scouting helps, you can find tracks on cattle trails fairly easy and check fences for hair, to find preferred entrances. The same tactic can be used to ambush pigs.
Navin R. Johnson: "He hates these cans!!!! Stay away from the cans!!!!"