Get a Demo: The first thing you will need is a demo of your voice over skills. You can find a local sound studio and call and ask their rates, tell them you are new voice over artist who is making a demo and you are on a limited budget. All you will need is 30 minutes of studio time.
Record the Demo: Find some advertisements in magazines and practice reading them aloud using different voices. You should have a variety of voices on your demo. Your demo should not be longer than 2 minutes in length.
Find an Agent: Search online for the nearest voice over talent agent. Get their address and mail them a copy of your demo CD along with a cover letter explaining that you are "seeking voice over representation". You can mail your CD to multiple agents at one time or you can even email an MP3 file to them if they accept new talent submissions this way.
Look for Work Online: If you are not accepted by an agent or you do not have one in your area, you can find voice over work on websites like Guru.com and Craigslist. If you do get a job however, you will need access to a studio to record the work. The fact is that if you have a good voice and you stick with it, you will eventually get work as a voice over artist.