Got a denial letter for unemployment, what now? - any advice?

My claim was denied after 10 weeks of waiting, and the letter says I have a short window to appeal. I have read a lot of threads here and could not find my exact situation. My employer's version of events does not match mine, and I have emails that show it. If you have appealed before, what helped you prepare?

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.

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.