Well Larry, my rule of thumb is to use the least amount of discrimination as possible. However, my favorite mode is the jewellery mode. But, when working areas such as sports fields ie soccer fields, baseball outfields and wide open spaces I like to hunt in zero discrimination. I am always curious as to what kinds of metal objects are out there. Usually the signals aren't too frequent so its not a problem. Most of Garrett machines amplify the audio, so that even the weak signals are nearly just as audible as the strong ones. This is a good thing, as you can hunt with the audio turned down quite low and not really miss any signals. You can however distinguish the slight differences in the tone. For example, a nickel has a smoother signal as compared to a pull-tab, even though they sound off at the same notch. I suggest you hunt always using the bell-tone. Most coins will give this special tone, and so will pop cans. But pop cans if shallow will give that over-size ring, similar to the sounds of a telephone ringing. Of course, you can always use the imaging feature too. Set your sensitivity as high as you can without the machine becoming too unstable. The stock 9" coil is very sensitive and a lot of users tape the coil wire straight up the shaft for the first 14". If the coil wire is lose and you bump the coil, the movement of the wire will sound off the detector, and it usually reads in the coin area. But, that's the nature of the beast. It takes a bit of time to get used to the GTI Series. Another rule of thumb is to always make sure the coil is dead center over the target when imaging or pinpointing in order to get the most accuracy. These are some of the basics. It takes time to develop an understanding of what the machine is trying to tell you. This machine in the hands of a proficient operator will find incredible amounts of good treasure with the ability to leave the junk in the ground.
Good luck with your new machine Larry. if you have any further concerns, please ask on this forum.
I can't imagine being without the sizing ability anymore, granted you need to size the target from 2-3 sides but it sure beats digging junk.
