First, take a deep breath. Having done so:
Arrive appropriately dressed (no shorts and flip-flops). Bring photo identification (for entry), a hard copy of the writ of summons and its exhibits, and arrive at least fifteen minutes before the scheduled hearing time; have coffee in the cafeteria, observe the courtroom, absorb the atmosphere, and alleviate tension.
From the moment you enter the courtroom (and ideally, as a way of life), conduct yourselves respectfully towards all present; from the defendant, through the court clerk, to the judge. The assumption that whoever shouts loudest is right does not hold true in court.