Get a vocal coach. Singing rock music takes a powerful voice. A vocal coach can teach you how to expand your vocal range. She can teach you techniques for warming up to avoid damaging your vocal cords. A vocal coach will also teach you to sing properly to achieve the power a rock singer requires.
Follow an alternative voice-lesson method. Sometimes a vocal coach may not be affordable, or you may not be able to find one locally. You can purchase a rock vocal course and self teach yourself. Jim Gillette's Vocal Metal Method (see Resources) has been around since the early 1990s. Metal Method is a strong vocal course that uses scales and advanced exercises to teach vocal technique, singing power and ear training.
Develop stage presence. This comes from working on your confidence and the way you perform when you sing. All good, successful rock singers have attitude and charisma. Freddie Mercury of Queen is a good example of a rock vocalist who was an accomplished singer and showman. Consider the image you want to present to the audience and be consistent with it.
Sing in a band. Singing live is one of the best ways to enhance your abilities. Singing scales and working on breathing technique are essential, but singing live forces you to use that training.
Record yourself singing both alone and with a band, then listen to the playback. It's hard to hear where you're weak while you're singing. The recording will help you pinpoint where you need improvement.