The best mode is true all metal mode, using some positive threshold. This setup will give you the "BEST" importunity to get those little nuggies and the greatest depth. Any you will also pick up everything......nails, spent bullets etc. But the target will still be ID'd on the face of the detector, and using the iron audio turned on, will allow you to ID iron with it's low audio grunts. All other signals you should dig, as lead can sound off as a good gold signal and coins can be both a silver or copper object.
Don't forget to use your ground balance range adjust, a great feature on the Garrett Gold.
Your next option to hunt is using DISC 1, which is similar to the pro Mode on the AT Pro. You can pretty well hunt listening to your targets. If you again hunt with your iron audio turned on to alert you of the iron junk, and ignore the high tones ( you will miss coins though) and only dig the mid range audio with the VDI numbers in the 40's. 50's & 60's. This second option will not be as deep as using the all metal mode.