^ what Sheridan said (starting to see a pattern with your "help me learn to call coyotes" posts amigo! haha)

To add to that:

Wind is absolutely key. As a rule of thumb, I would rather skip a hunt than run a set with the wind in the wrong direction. With the wind in the wrong direction, my odds of drawing in a coyote are low, but my odds of them getting my wind before I see them and get a shot are high, meaning I'm more likely to educate them to my call than I am to get a shot. I'd rather stay home than teach a coyote how to avoid my bullets.

Move slowly in your set. Even simple stuff like turning your head too fast can give you away. One KEY time is when you take the call away from your face.

Don't call too long for each series. Spend your time watching, and less time calling. A 1min series really IS better than a 2 min series. A dog will know EXACTLY where the sound is coming from, and they'll come right up to the edge of their cover, stop and look for the call, so if you call too long, they'll have a chance to spot you before you spot them. Same rule applies for E-Callers, except you have the luxury of using a decoy and camoflaging your caller well, and using the visual cue in your favor.

Having a partner is generally a good idea, day or night. Two people can see so much more than one, and it lets one guy focus on calling, and the other focus on watching, then shooting. At night, they can help run lights as well.

Night calling is basically the same as day calling, but with their confidence more amplified, and your visibility reduced. I run the call less at night then during the day, to give myself more time to watch.

Where legal, use a red or green filtered spotlight, and pan back and forth with the outer edge of the halo just dipped into the grass. You will be able spot the glare in their eyes this way, without shining the light directly ON them which might spook them. You can take a helper to run lights, or try to run them yourself. When I call alone, I hold the light high until I have a shot, then drop the bright center spot onto their body, and take the shot. Some guys will hold the red light on them until they're ready to shoot, and lip on a bright white light for the shot. Either way works.

If lights are NOT legal, then a 50mm objective, 30mm tube, illuminated reticle scope in relatively low power (2.5-7x, 3-9x, etc) is a good option to help improve your visibility for shooting. Set the reticle intensity very low, so you don't "wash out" your target. Moonlit nights are best, especially over snow cover. A clear starry night over mud can work, it's just very hard to see anything. 1x up to 4x red dot scopes are a good option as well.

A shotgun with buckshot is sometimes a better option at night also. The action is often faster and closer, and your visual accuity is poor, so the ol' "point and click" is sometimes a better option than a scoped rifle. 00buck out of an improved or light modified choke or T or No 4 buck out of an extra full (turkey) choke.