Favorite baits lures/scat: I typically stay away from baits of any sort. I’ve had far more success with gland lures. I typically use two different lures at a set. One “call” lure and one mild lure. Post and flat sets have worked the best for me, and the terrain dictates which I use. I’ll through out an occasional dirt hole, but I find them to work better for fox and raccoon. As far as using scat, I refer to it as gold. If I have any available, I will use it as “fencing” for the trap. Post on the upwind side, trap bed, and then 2-3 inches downwind of the trap I will place the scat. Give the scat a little shot of urine to freshen it up. I hope that makes sense.
trap size chains and stakes: for coyotes I like #3 sized traps and MB550’s. I really like the MB’s. I also use modified Bridgers. Don’t rule out Dukes either, they require a bit more modification but are very solid and inexpensive. I run 2 and 4 coil, and honestly don’t see much of an advantage to 4coil. Solid pan tension and good bedding is far more important than the spring strength, IMO. I like very short chains attached to the center of base. Three inline heavy Swivels, with 2-3 chain links between each swivel. I use two staking methods based on the terrain. If I can drive a stake, I prefer the bullet point style stakes made by fox hollow attached to 16” of chain. I keep these chain stakes permanently attached to the trap chain. The second method I use is a quick build/release cable system that I can wrap around a log or something heavy to create a drag. It’s very light and works very well with things you find outside. I would be happy to provide details.
Locations/scouting: scouting is pretty simple, like others have said, look for tracks/scat/coyotes. Locations can be a bit more complicated. Rolling hills with not a lot of big saddles or transitionary zones I like to set in the low spots between hills. If the vegetation is low to the ground, a post set is my go-to. And make the post very obvious. Try to determine the predominant wind direction and make your set on the downwind side. As far as actual sets, I like to leave the dirt covering the pan lower than the surrounding area by about half an inch. Don’t get carried away with fencing around the trap, less is more. With bobcats you can literally outline the whole trap and it helps, but coyotes are more wary. Timbered areas (and all areas) I look for natural funnels and make my sets there. Washes are great, and I’ll make sets in the narrow points and also the areas of entrance/egress to the wash. Look for the paths of least resistance, and those are your likely hot spots.
Dens: active dens are very very obvious. They are also used for very brief and specific periods of the year, so in my opinion are not worth the effort of looking for UNLESS you are doing specific control work or trapping in late spring. Dens are a whole other animal in it of themselves.
I love talking about trapping and am happy to share knowledge.