These wont realy help you scream or growl, but they will help you a little on stage. Especialy for people new to singing, or new to being on stage.
1. When you sing, and you look stupid, most of us do, use one hand to hold the mic, and the other to cup it over so you get a sort of echo outta the mic, and no one sees your mouth so it doesnt make you look like a retard.
2. If you have longer hair, like I do, slop it over into your eyes, and over your mouth, you look badass, and its not foucsed on your mouth, so people dont see that "O" shape you make while singing.
3. Move around, dont stay still the entire show, watch some of your favorite singers and watch how they move around on stage. Just try not to trip over the chord from your mic to the amp... Also utilize your equipment, if you have and amp to jump on, do it. If you have a means of getting hurt, do it. Its all for the metal buddy...
4. If your not able to sing a song perfectly at a show, dont try to hard to do it. The best thing about a live performance is the fact you have a guitarist, bassist, and drummer with you. All the attention isnt on you, so dont push it full on, unless your say Bones98 and that kind of shit is natural for you.
I hope this helped some people. Im just trying to put a few things ive found out from other bands, and from my own experinces up.
Also check out my band Auschwitz Thunder Pig
www.myspace.com/auschwitzthunderpig