I would also suggest visiting newgrounds.com if you make an account over there and upload some sample clips people can give feedback and let you know where you stand. It doesn’t matter if you are really good or not when you start doing this what matters is that you get feedback and improve on it until you are good. No one starts out all that amazing usually but if you have the potential and you keep at it there is no reason you wouldn’t be able to do voice work. Try heading over to newgrounds and check out any other voice acting places you can find and just put examples of what you can do out there.