Denied unemployment, how do I appeal? (Phoenix)

I got a denial letter last week saying I left my job voluntarily, but I was let go as a customer-service rep. It has been a long 14 weeks. 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?

Legal aid offices and some workforce centres help with unemployment hearings at no cost. A call is worth it.

Stay calm and stick to facts. Mine lasted about thirty minutes and felt more like a conversation than a trial.