First off, if you want to check to see if you have a good working CZ, put the 8 inch coil on, set the GB ( ground balance) to 5, discrim at 0, sens at the 3-4 range, volume at 7-8 and you should get a solid repeatable high tone on a clad dime air testing in the 9-10 inch range.
When hunting, make sure you ground balance either using the bobbing method (how to do it is in the manual, and there are youtube videos as well), or the quicker pin point metod and don't run with the sensitivity too high. Stay in the 3-4 range...no more than 4 to start. Also, make sure when you gb using the bobbing method, that once completed, turn the sensitivity back down into the 3-4 range.
If you are going to hunt in discrimination mode, make sure you use 0 so you can hear/listen to ALL targets ( including iron) to start. Hunting in this mode will help with getting fooled by deep iron that may wrap into the high tone. On those targets you will hear low tones mostly, with the possibility of an occasional high tone. If you use any other discrimination level (1,2,etc.), the low tone of iron is not heard...yet if it wraps into the high tone, you will only hear the high tone and think it is a good target.
To start off, only dig high tone repeatable targets that continue to hit as high tones from different angles. Any target that hits as a low tone 50% of more of the time, leave it for now. As you get better using the machine, you may want to dig some of them up....especially the deeper sounding targets ( the audio modulation on the CZ running in volume from 1-5 is a cool thing to help tell shallower targets from deeper ones). Some deep sounding low/high hits can be deep silver, so if you are hunting places where older silver coins can be lurking deep, it may benefit to dig those low tone/high tone bounces.
Experiment with the pin point button....sizing a target using that VCO pin point button via detuning is an art form and once you master that, you will learn the difference between round type targets and bigger, elongated ones.
Use the 8 inch coil to start....then the smaller 5 inch. The bigger 10.5 is good for open areas and beaches.
In my opinion the 8 inch coil on a CZ is the optimal coil.
Hope this helps.