Denied unemployment, how do I appeal? - 21 weeks in

I got a denial letter last week saying I left my job voluntarily, but I was let go as a bookkeeper. I do not usually post, so bear with me. The letter lists a deadline and a hearing process, but it is hard to follow. 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.