Denied unemployment, how do I appeal? - what worked for you?

I got a denial letter last week saying I left my job voluntarily, but I was let go as an operations analyst. There are 14 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?

Thanks for writing this out. I went through something close to it last year, and it got easier 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.