Got a denial letter for unemployment, what now?, accountant here

I got a denial letter last week saying I left my job voluntarily, but I was let go as an accountant. 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?

File the appeal before the deadline, even if you are unsure. You can gather documents afterwards. That is the one part I would not wait on.