there are a few different types of 'scream', but in general if you want length and quality it all has to come from the lungs, keep the throat out of it.
if you have a sore throat afterwards then not only is it being done wrong but you will damage urself. I personally have no problem with long screams because i'm a piper and therefore i am made almost entirely out of lung, with a few limbs here and there.
bands i like that scream (either as main vocals, or just time to time):
Lamb of God (heavy metal)
Cult of Luna (doom)
Rosetta (doom)
Callisto (doom)
Boris (Japanese Noise-Rock)
Biffy Clyro (just plain good)
Tool (prog rock)
A Perfect Circle (prog rock)
ISIS (doom)
Opeth (jazz doom)
Rage Against The Machine (rap-rock)
Tool screams are the best way to practice, Maynard can just hold it for aaaaages.
although the earlier Lamb of God stuff, when they were a 3 piece known as Burn The Priests, Randy Blythe manages a 32 second full on gut roar its nice.
