Record a demo of your band. You can do this on home recording equipment or go into a professional studio. A professional studio is the better choice, unless you have sufficient sound recording equipment at home and the talent to use it. The demo should consist of five songs. This will be your calling card for whatever you do musically, whether you're trying to get your band a job playing somewhere or get an agent or record company to listen to you.
Look for an agent. There are several ways to do this. Use an online artist management database to do this (see Resources). You will need your demo and a band biography when you approach an agent. Include a short letter introducing yourself when you submit your demo and biography. Include any musical accomplishments you have in you bio, including any paying shows you do and any contests you've won. Follow the submission guidelines of individual agents when you submit your demo for representation. It isn't necessary to have an agent to succeed in the music business, but it gives you a leg up on the competition. Agents have the contacts you need, and many record companies won't pay attention to you without one.
Perform anywhere you can, including contests. Many battle of the band competitions feature not only cash prizes, but often a recording deal as well. There are always current listings for these competitions online (see Resources). MySpace is a big supporter of the independent musician as well. They've even launched their own record label and allow users to vote for the bands they will sign next. This is a back door into the record business that could lead to your big break. MySpace can expose you and your band to talent scouts and open up an entire audience for you.
Promote yourself whenever possible. Consider recording your own CD and selling them at your shows. Make T-shirts with your band logo on them. Part of making it big in the music business is having a following. Word of mouth can go a long way. You have to work hard to succeed in the music business, but with persistence, your hard work can pay off.