You don't have to do anything but touch the deer. Then the deer is safe from coyotes that night and maybe the next night. Because of trappers. So think about it when you're trapping coyotes. Check your traps from a distance using binoculars to keep your scent down and you will catch more animals.
Lures are attractors to bring the animal over to take a look.
Because animals are sometime fussy, you use lure that is blended together with different ingredients. Out of all the different ingredients it only take one to make the animal dig. Lure is hard for beginners to understand. It is an attractor so in order for it to attract, the animal has to smell it. There are of course different things that effect how much lure to use and when to re-lure.