****ing belt it and put emotion into it. thats all you need to do. no matter what comes out as long as you are putting ass behind it, it should be cool.

make sure your voice doesnt crack though.....thatll be embarrassing.

Build your lung capacity as much as possible with simple breathing exercises - Serj from SOAD can sing for an unnervingly large amount of time. If you get into a face melting scream that doesn't die after the first 5 seconds because you're running out of air, it has a much better effect than you ending up spluttering on stage. Work on keeping your vocal chords open if you're doing a gutteral scream and sing from the diaphragm, because otherwise your voice is gonna hurt. If you're gonna try a high pitched scream, don't strain your throat. Again sing with the diaphragm not your throat, or you're gonna be doing some hurting. If you can reach the pitch you want straight away, slowly work your way to it by starting withing easy range and working up.

Then why not try giving advice as to how to scream without being voiceless, rather than just bashing?

I use the throat technique when I scream (there is a right and a wrong way to do it). It gives you more of a gavally sound. As far as pitch goes, that really depends alot on on how you have your tounge, chest, and mouth positioned. Just try different things till you get the sound you want. Also, not that you want to be a rip-off, but if you have a band that you like how they scream, try to scream along with them. May take some time, but it will help you get towards your goal.

screaming techniques-

take in as much air as you can so you don't get lightheaded-i tend to get kinda dizzy if i don't get enough. for me personally, a beer seems to help me before i sing, but especially if i'm belting. i can't think of much else.

Please tho whatever you do dont try and become another Dani Filth coz him and his screaming vocals along with his band 'Cradle Of Filth' are awful

scream from the heart.......*makes a boyband hand gesture*

Some good points there. I did a bit of drama training many moons ago, and we were taught to concentrate bringing sounds from the centre ie, the belly. This can be done as mentioned already with breathing excercises, also do vocal warm ups prior to performance. Don't put to much into vocal warm ups prior to gig. Save something for the main performance. Gargleing with salt water on a daily basis is recommended for all vocalists.
Here is a good vocal warm up/tongue twister you could try.

Theophilus Thistle the succesful thistle sifter, when sifting a sieve full of unsifted thistles thrust three thousand thistles through the thick of his thumb.

also, no soda before a show. or milk. you have to do the same preparation as with singing.

Milk can be good for proctecting your vocal cords as it builds up mucus around then and minimizes damage. It'll also screw up your pitch if you're singing aswell though and thats the problem.