Use everything you have. Camera, compass, tape measure, electronic equipment. It's very difficult to find the place you need to dig. And there are decoy trap spots.
We dug a decoy spot up a while back, (last winter I think) I'll try to post some pictures when I have the time. Had a nice 4-5 foot square flat floor like vault lid at about 7-8 feet down. We were lucky we had an excavator on private land, because to lift the lid you had to spring the trap that wasn't really apparent. Got pretty excited when we found the lid... but nothing under it.
It was a spot pretty well marked off a A-frame/ pyramid boulder near an old trail near a creek bottom. If you knew what to look for and knew what bearings and distances were commonly used on other sites ( it think it was 15 varas off the A frame at 300 degree bearing , can't recall for sure).. With a couple other boulder markers above ground, including a "stop" desk sized boulder with a 90 degree cut out on it .
No auras, didn't have the time to try and get one. Kind of opportunity knox from a friend who knew someone with land and saw the A frame on 4 wheeler out riding his property. Just some markers and some knowledge of surveying that was commonly used was what we had to go on. It probably could have whacked us if we were hand digging it, but I doubt we would have dug directly under the boulder up top the extra 18" or so needed once we got to the lid to lift it , which would have collapsed it all. Sometimes you just go with it if you can get an excavator in. We tried to detect it with a 98" PI coil, and no certain hit, but the math seemed to work and we were there with an excavator, so, we figured might as well try it since we were there with all the equipment.