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. Trying to rip a scream with vocal folds that aren't properly prepared can leave you feeling raspy. Pushing your voice beyond what it is ready to do can lead to swelling and even damage, much like an athlete stands a much greater chance of injury when forgoing a pre-game warm-up. There are many warm ups you might use, including:  Regular scales at two octave intervals. Sing regular intervals from low in your range up two octaves and back down again. You can check your intervals by playing along with a piano; each white note step is corresponds with a one-interval step. Sing trills. This will warm up the muscles of your tongue and lips. Simple sing or hum a tone while you trill your tongue or lips. For your tongue, this will be a rolled sound like the 't' in 'water' or a Spanish 'rr.' Lip trills are like blowing a raspberry. Siren up and down. Use a vowel to gently ascend from your lower range all the way up to the your upper limits. Then descend in a controlled fashion, as smoothly as possible. While a certain level of fatigue is normal when training your voice to sing a broader range or in a different fashion, as you are in scream-singing, you should listen to your body. If you feel pain, irritation, a burning sensation, or notice uncharacteristic changes to your voice, stop immediately.  Pushing your voice can result in permanent damage. Long periods of rest can cure fatigue and minor strain. The strain you put on your voice while training it to scream-sing can lead to hoarseness and discomfort, but the same sensations can come about from normal intensive vocal practice. You should break up your practice sessions so that you're not overly straining your voice and doing potential damage to it.  Hydration is important for the health of your vocal folds. Use breaks to grab a drink of warm water or tea. Beginning singers will want to limit singing to about 20 minutes per day. With experience will come greater vocal strength which will translate to more practice time throughout the day. Even advanced singers should limit practice to several 15 - 20 minute segments. Each segment should start with a warm up, end with a cool down, and be followed by rest, and hydration. Serious singers will probably want to get a pre-evaluation from a medical expert to address an avoidable issues before they can cause damage. Some doctors specialize in treating the pathologies common to vocalists, including vocal fold swelling, nodules on the vocal folds, and hemorrhages. If one of these specialists is not available in your area, you should seek out an ears, nose, and throat doctor, explain your situation, and ask him to evaluate the condition of your voice.  You should also see a vocal professional if you experience vocal discomfort or an uncharacteristic change in your voice for an extended period of time. A laryngoscopy is a procedure frequently performed on professional vocalists, where a small camera is used to inspect the condition of the vocal apparatus. A voice coach will have the experience to recognize production errors on your part when you try to scream-sing. This will allow you and your coach to isolate problem areas and protect your voice from overexertion and damage. Some experts even specialize in teaching scream-singing.  You might look for a voice coach in the music department of at a local university. Seek out a voice coach at a local music school or institute. As a more affordable option, you might make use of video coaching. Some voice coaches provide pre-recorded videos for a fee, including helpful techniques on these recordings.

Summary:
Warm up your voice always Avoid unpleasant sensations. Take breaks for your voice frequently. Consult a doctor or expert to evaluate your voice. Hire a voice coach.