New to the game with a Minelab GPX4500 Gold Machine? You have a depth advantage over most already. What coils do you have? Use your General / Normal settings at first. Become comfortable with ground balancing and keeping it balanced. It's a mighty difficult machine for a first, but you'll soon get the hang of it. Preset Operating Modes: Minelab's "GPX 4500" employs a number of factory preset operating modes that allow you to starting detecting right away in a range of field contexts. These include the:
"Custom Mode" that you can set up based on your own needs or preferences.
"General Mode" which is for basic operating conditions.
"Deep Mode" for those hard-to-reach targets buried at depth.
"Hi-Mineral Mode" which is typically employed in "hot" or highly mineralized locations.
"Hi-Trash Mode" which is pretty much self-explanatory.
http://vredenburgh.org/desert_fever/pages/imperial_county_01.htm
Good luck!