My first suggestion is record your own voice.
Listen to it on tape.
The way you hear yourself speak is different from the way your voice sounds to others.
Listen to your own voice.
Then listen to other people.
Take a class that teaches technique and provides you with tape of your performance.
There are several reputable voiceover workshops,
but always compare and get a referral from someone you trust.
Once you've learned the technique, you need a great Demo tape.
Hopefully the class you've taken has provided you with a good beginning.
Otherwise you've got to get a professional demo!!!
(Don't try this at home, unless you've got your own recording studio.)
Next, find a voiceover agent.
If possible get a "House CD" from different agencies.
A "House CD" is a demo compact disc or discs featuring the agency's voiceover artists in 2-3 minute segments.
In addition to letting you know who the agency represents, a "House CD" will let you know if there are conflicts or holes in their roster.
Submit a professional Demo tape to the appropriate agent.
Call to make sure they've received your tape.
(Don't expect them to listen to it unless you ask them to, and don't expect to ever get it back)
Follow up in two weeks time with a phone call if you haven't heard back.
You can also submit to the voiceover casting directors,
there are only a handful and the voiceover community is relatively small.
The same people tend to work again and again,
and casting directors will usually call in only voices they know.
Voiceover, ADR(audio-dialog replacement) and looping can be extremely lucrative.
You can earn SAG scale for 4 hours work, plus residuals.
A friend of mine has done national voiceover campaigns for "Carl's Jr" and "Chrysler Plymouth",
and is the voice of "Captain Planet".
His voiceover work enabled him to buy a nice house, a nice car and a lot of nice stuff.
He works regularly and is constantly auditioning.
(yes you still have to audition for voiceover work by submitting copy on tape)
