Appeal deadline questions after an unemployment denial - any advice?

My claim was denied after 15 weeks of waiting, and the letter says I have a short window to appeal. There are 8 people counting on me, so I am trying to be careful. 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 saved me later.