I have never done this kind of work before but you have to start somewhere right? In my drama classes in high school I used to pick monologues that should be set in places other than florida so that I could try out voices. Friends and family have all told me I should try to get into this line of business. When I answer the phone everyone, including my father, confuses me with my mother because I can have that older quality, professional and busy mom voice as well as the voice of someone in their early twenties. I often times take people by surprise when I start talking in my little kid or cartoon voices because people don't expect it, they think it is interesting or weird that I can do that kind of a voice.
I've had no formal training besides drama classes in high school. However, I have always had an ear for other people's voices and try to mimic others as much as I can. I pick up on slight hints of an accent and try to perfect those words that I notice are different and build a 'character' out of it. I also listen to actors who do voices like Robin Williams and try to mimic voices that he does and make them my own.
I am a college student who has some time on my hands. I am constantly seeing different people and trying to study them to understand their voices, word choice and and overall character for acting skills. I have stopped drama classes since college but I hope to continue them again next fall.