i been practicing my scales lately, also tried the whisper siren
but resonance is tricky. i do the big dog/little dog thing, but i'm not quite sure i'm doing it right.
as for vowels, uh??
they say your tongue should be higher, like you should say "keeey" and say "toward" with your tongue up there. but it can't be rigid and you have to find a place for your other vowels? like, just normal but higher tongue? i do not physically grasp a lot of this stuff