Decide what kind of band you want to be in. Heavy metal has grown from its hard rock origins to embrace countless sub-genres, including hair metal, power metal, speed metal, and death metal. Singing styles vary tremendously from one genre to the next, so it is important to know what kind of singing to practice when you go out for an audition.
Assess your vocal abilities. Get an audio recorder, tuner, and metronome, and try to emulate some metal singers you've heard. Learning the screaming vocal style employed in certain types of metal can be difficult, since it requires that you put intense strain on your vocal chords for a long period of time. Listen to your recordings, and correct any mistakes you make, such as hitting notes sharp or flat, or falling out of time with your metronome. A tuner will help you determine whether you are holding a note in tune or falling flat or going sharp.
Practice. Whether you're an amateur or professional musician, the rough, gutteral vocal style of metal can be hard to get used to. Keep recording yourself and listening to notice areas for improvement, such as agility, range, and vocal quality. It is important to build up the stamina to sing songs from start to finish, as this will likely be asked of you if you get an audition to front a band.
Search classified ads for auditions in your area. Craigslist, metal zines, and even your local daily can be good places to find band auditions.
Contact the bands listed on the ads you found promising, and ask them what they are looking for. If you are in a large urban center, there will likely be scores of bands holding auditions, and it would be very time consuming to attend all of them. Limit you auditions to bands that appeal to your tastes, and who seem serious and professional.
Attend your auditions well rested and dressed appropriately. Image is highly important in many genres of metal, and it is best not to show up to a death metal audition, for example, dressed like David Lee Roth. Also, it is better to re-schedule an audition than to show up in less than top form. Experienced musicians will understand if you talk to them about fatigued vocal chords.
Take the offer that looks most promising. The band that contacts you first might not be the band you want to work with the most; wait a while to hear all offers. If you did not get any call backs, consider practicing more, or holding your own sponsored audition for a band.