Here are some pictures from some setups from yesterday and today...
This first photo shows some superficial feeding tunnels in a lawn area. These tunnels are the reason the client called, but probably aren't the best place to set the traps. You could set them here, but best to check around and see what else you can find first.
Same yard as first photo, about 10 feet away from lawn, there is a very shady and damp area with a long wall running the length of the front of the property. There's about a 99% chance that there's going to be a somewhat deeper travel tunnel along the base of that wall. No signs of activity on the surface, because the tunnel has been in constant use for a long time, and all surface signs washed away long ago. This is a great place for a set up.

OK, here's the basic set with my traps. Just dig out a 4 or five inch segment of the tunnel, and place set traps both directions in the exposed tunnels. Push the traps into the tunnels at least far enough that the trigger pan is inside the tunnel. If you keep a finger against the back of the trigger pan, you can prevent the traps from firing as you push them in. Usually I can get them far enough in that the spring on the back of the trap is half way or all the way into the tunnel. Bed the trap into the soil a bit by pushing down on the spring or the spring catch on the back of the trap. Finally, block off the exposed end of the tunnel behind the trap with a dirt clod or compacted mud ball, and filter loose soil over set to exclude light.

Another good setup location. These are brand new tunnels in a flower bed that had just been worked and watered in preparation for some new plantings. The moles moved right in. There were obvious fresh signs on the surface, unlike the deeper travel tunnel shown next to wall in above photos. But I like setting on straight tunnels along walkways or other obstacles.
And what's that green thing at the top of the picture?

Oh, run for your lives, moles, the evil molechaser is going to get you. I catch moles right next to these things all the time.