Select the freshest or most central mole mound.
The best way to find the freshest mound is to level all of them off then the next day set your trap at the new one that has popped up.
When leveling off the mounds be sure to spread the dirt out not flatten it. This will keep the grass underneath alive.
If you are only seeing raised tunnels and no mounds. Step on the tunnels to flatten them and eventually you will feel the spot where the mole goes down. That's where you will set your traps.
Flattening these raised tunnels is also important for keeping the grass alive.
Download the PDF instructions from the back of the packaging here.