Denied unemployment, how do I appeal? (update)

My claim was denied after 21 weeks of waiting, and the letter says I have a short window to appeal. I do not usually post, so bear with me. I have not done a hearing before and I am nervous. If you have appealed before, what helped you prepare?

Thanks for writing this out. I went through something close to it last year, and it settled down once I kept a simple log of every call and form.

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.