I started on the radio as a disc jockey, and used a variety of voices for commercial productions. I moved to the stage as a character actor, doing whatever sort of voice was needed for the story. I found using varied voices helped me in sales and business presentations as well, and in recording radio commercials for the company I worked for. I became a preacher, and used character voices in the pulpit to make points in sermons. Now, I'm starting to use my voice to earn a living.
I have years of experience and almost no formal training.
I've been speaking for almost 59 years. I've had stage directors help me perfect the voice they wanted for roles. I worked as a disc jockey, and used voices. Of all the various things I've learned, learning how to follow directions to give a director or client what they wanted is near the top of the list. I'm also good at presenting a variety of options to those who might not have a preconceived idea of what they want, but will recognize it when they hear it.
I own a decent USB microphone and software to make a clean voice track. I'm not an audio engineer.
I can follow a script to the letter, or I can ad lib around one, depending on what the client wants.
I also learn things very quickly. When called on to do a narration about an industrial process once, I researched the process before I did the narration. Being knowledgeable about the subject helped me to sound like I knew what I was talking about.