Demp try running your pans at 9 and 2! 9"s back from your hole and offset 2"s right or left. If you're using a larger/ taller backing then back your trap up even more.

Make sure your traps are bedded solid! ROCK SOLID! Any movement at all will cause critters to dig.

Make sure your pan is level and there's no creep in it before it fires when set. You can do this 2 ways with the Duke traps. You can night latch them or simply bend the frame the dogs attached to up or down. Either way you want your pan sitting level and firing with less than 1/16" of movement. You can also wrap wire around the frame where the pan connects to take some of the pan wobble out of Duke traps.

Coyote urine will not deter other predators from working your sets. I use either coyote, fox or bobcat urine on every set. All it takes is a few drops on your backing.

Bait and lure go a long way as Wade said. Commercial baits use a butterbean sized glob on a piece of sheepswool down your hole. If you're using commercial lures dip a q tip in the lure and you're done. I normally use either a bait and lure combo or 2 lures at each set.

Learn all different types of sets, I've seen dirt holes, compass sets and flat sets mentioned here but learn to make more. Walkthrough sets are deadly, stepdown sets are perfect for fields where coyotes or other critters have already been digging. Don't get hung up on any one set.

You'll develop your own style of making sets and it'll all fall into place.