Got a denial letter for unemployment, what now? (update)

I was told my separation was for misconduct, which is not what happened. It has been weighing on me all week. 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 11 months ago, and it got easier once I kept a simple log of every call and form.