I did my first regional radio ads when I was in my early twenties, 30 years ago. I was working as a freelance illustrator and graphic designer for local ad agencies and a client recognized me from area theater and asked me to record some ads. I had no training then and the ads were done at a local radio station. Later, in the 90s, an actor friend got me a job recording an audiobook, "The Wealthy Barber" for PBS along with 3 other actors. I've gotten much more serious lately about voiceover, taking classes and learning to record with advice from friends- DJs, radio engineers and stage sound designers- who knew production.
Classes with Bettye Zoller, Terry Clark Linden and Pamela Lewis.
I use Sound Studio, Audacity and Macintosh Garageband software for recording and editing. A small mixer, and an assortment of mics of moderate expense (Shure, etc.), but good frequency range for voice. I have a good collection of CDs with sound effects and licensed music, or can make music beds with Garageband.
I have been an Art Director and copywriter at three ad agencies, and as a freelancer, I've done illustration, storyboarding, graphic design and copywriting for many ad agencies and businesses. I've been an actor for 30 years, nonunion by choice (I live in Michigan and there's more nonunion work) although since being in a number of feature films in the last couple of years (there was a tax incentive here for a while) I have become SAG elligible.