well make sure you're not inhaling =Þ
like, close your throat as much as you can, and push deep from the diaphragm. the harder it is for the air to escape, the more tone your scream will have. but be careful with screaming. make sure you dont force yourself to scream too hard, or you can do some damage. also, once you start, after about a day or two, you should get this wicked sore throat, thats normal. it'll last everywhere from a few days to a week (mine lasted a week), but when it starts, dont stop screaming, keep going, and it'll condition your throat to do it better, and more. once it goes away, scream at least a few song lengths every day, or else when you start up again, you'll get the sore throat... and i'd never wanna go through that again.