Perform everywhere you can. This is one of the most important steps to take to pursue a singing career. No one is discovered sitting in his bedroom. You need to be visible. Sing at church, weddings, parties and in clubs. Make a performance video and post it on Youtube. Consider putting together a website that features samples of your songs. The more you're seen performing and heard singing, the better chance you have of someone discovering you.
Record a demo. You can do this in a professional studio, or if you know someone who has a decent home studio, you can record there. The demo should include five or six songs that demonstrate your singing range. Include a couple of ballads, a couple of fast songs and one that shows your vocal range and technique. Burn the demo onto a CD and produce several of them. These will be your calling cards as you promote yourself to record companies and managers. Consider making a performance DVD as well. If you do a show somewhere, have someone record it for you. Managers will not only take in your singing abilities, but the way you handle an audience, too. Burn several copies of the DVD as companion pieces to the CD.
Get a manager. You may not think you want to share a percentage of your profits with a manager, but having one can bring you more work than you can get on your own. An effective manager can open doors for you that you may not otherwise be able to open. Before you sign with a manager, ask them to provide a list of clients he has handled successfully.
Consult an online database (see "Resources") or an industry contact book such as the "Music Phone Book." Remember that you are selling yourself to a manager more so than he is selling himself to you. You need to present a professional demo with an attitude that shows a prospective manager you've got something he can sell.
Keep your eyes open. Look for managers and record labels on the back of CDs by your favorite artists. Don't be afraid to send your demo out to these contacts. You only fail when you don't try.