Try a shorter and slower sweep to help separate the junk. Things at the coil edge can also signal, so if you have a lot of things under the coil you just have to take your time to learn about it. Try hunting in in a cleaner area at first or maybe toss down a few sample targets into the junky spot to see what a "good" signal should should sound like amongst the iron.
Or just dig all the signals you can from a spot and keep resweeping. It shouldn't take too long to learn what's happening. Air tests are good too, so you can see how all sorts of thing read.
-Ed