Denied unemployment, how do I appeal? - 11 weeks in

I got a denial letter last week saying I left my job voluntarily, but I was let go as a bookkeeper. I am in Phoenix, in case local advice matters. I have not done a hearing before and I am nervous. If you have appealed before, what helped you prepare?

Stay calm and stick to facts. Mine lasted about thirty minutes and felt more like a conversation than a trial.