You can do natural harmonics by slightly touching selected notes (the easiest one for practicing the 12th fret, but you can try the 7th aswell). What youre doing by that is youre "splitting the string" into two (if youre playing the 12th).
ps: I learnt it here
" Now therefore kill every male among the little ones, and kill every woman who has known man by lying with him.
But all the girls, who have not known man by lying with him, keep alive for yourselves. "- Book Of Numbers 31:17-18