ha, Rob is right: there's no shortcut to the school of "hard-knocks". I suppose though, that if you had someone around you with the same machine, and could trade off flagged signals, he could tell you "skip this and that, versus dig this and that". And he might tell you "because that's iron" or "because this one is a large overload" and so forth. But really though, it's still not a good substitute for the school of hard knocks. Because once you've dug up and stared at a variety of objects, making the mental connection between that, versus the signal it gave, only THEN do the lights go on, and you start to develop mental patterns. And just be aware that some items of a variety of values might share the same TID/tones. For example: a car key and a coin will be similar. A pulltab and a gold ring will be similar, etc...
Oh, and one final note: I had to chuckle when I read the title of your post about "explaining sounds". Because when you think of it, that's impossible in printed text. For example, no amount of printed text can explain what the sound of c-minor sounds like, right? It has to be heard. Same for when someone says "repeatable" or "bold" or "smooth" or "full". All such terms are arbitrary and nebulous. Because all those things mean one thing to one person, and another to another. Again, things that must be heard and seen (in conjunction with the way the coil is being swung, criss-crossed, etc... as to how the user is isolating various sounds).
So either pick a spot prolific with easy clad, and dig 300 signals. Or hook up with a proficient user in your area, to flag and compare signals.