How did you learn to do the "Cookie Monster" metal vocal style?
I have no idea. It was a natural progression as to what needed to be done. It was at a rehearsal with some band, there was a Cookie Monster part in a song, and someone didn't show up and I tried it. If you commit to it, you can do it, but you can't half-ass it or you'll hurt yourself. Some people inhale, which I can't do [inhales and intones a guttural HUURRRRRRRRR sound]. It's opposite to what your vocal cords are designed to do, and there's no power to it, as opposed to exhaling [exhales a much more earth-quaking OOOOHHH-WHAAAAA].
For a regimen before a show, I'll start with a saltwater gargle, some steam inhalation, then honey, then singing, then normal scales, then scales screaming higher, then scales screaming lower. You can't drink before a show, other than maybe one sambuca. When I'm fronting this band, I don't remember what happens when I'm on stage.