There is an important harmonic position omitted so far in this discussion, the one 5 frets up from the bar, it's the double octave. Used in this way, (Bar at third fret) Play normal notes then with palm stopping the strings partially at fret 15, then 10 and then 7. What you have is G, G octave, D higher, and then G double octave.
The second part of this page may be useful

And any of these videos will show me playing palm and finger harmonics, pretty close-up.
This video use harmonics a lot.
The ones below show you other aspects of playing? close-up..
Pat Mike and myself, not taking it too seriously and me acting the fool as per usual (as is my BAD intonation .. The head wasn't so good that day)
On YouTube Here :-
Lovely hula Girl
Witchcraft
To Make you love me Kuuipo
Midnight in amarillo
White Ginger blossoms
Ten Tiny Toes
Little Brown Gal (AGAIN)
Baz >:-)