Hmm, can't think of any more tips, lol, just make sure to keep water with you, and don't strain yourself doing it, if your throat starts to hurt, don't continue, give it a rest for a while ("For a while" is basically rest until it stops hurting)... I'm not the greatest myself, and haven't screamed for a while now, but meh... I've gone back to my guitar for the time being, lol.