I hunt coyotes primarily in the daylight hours during the winter months. The rest of the year I let them walk since fur is worthless. But, since fur is worthless price wise, spring can be very productive as well.
I have used e-callers and hand calls, but always end up going back to the hand calls. Like StillaKid mentioned, mouth calls can be made to sound more realistic than e-callers.
My favorite brand of calls are Primos and use a variety of howlers and rabbit distress calls. But, don’t overlook fawn bleats, deer calls, turkey diaphragm calls, or even elk calls. All of these calls can be made to sound like a critter in distress.
This time of year I like to let out a couple of lone howls and sit for awhile. If no response, belt out a short series of distress sounds and wait. How long you sit and call all depends on the terrain, time of year, and if you know there are coyotes in the area. SOmetimes they come in right away and other times it may take awhile. Almost every situation is different and experience will allow you to know which calls to use and how long to wait before moving on.
There is a lot to know to be successful in hunting coyotes. Sure, sometimes a guy gets lucky and gets one right away, but consistency takes time and knowledge.
What type of terrain do you plan on calling?