Focus on the issues before the court. If you filed a property tax appeal, the issue typically is the value of the property or entitlement to exemption of special assessment, not the amount of tax. This may involve legal issues or appraisal methods. If you filed an income tax appeal, the issue often is income, allowable deductions, credit for withholding, etc. Avoid emotional arguments and personal attacks on the other party.
Rational arguments based on facts are more persuasive.
Don't be afraid to ask the other party about that party's evidence or to share your own. Organize your evidence in a way that would help the court understand your position. Be prepared to explain how each piece of evidence supports your position. The decision is yours. The appeal process in the Magistrate Division is often less intimidating than a typical court proceeding.