Appearance should not matter in life.  Appearance certainly should not matter in court in the justice system but it does.  You should dress conservatively as though going to a conservative religious service.  The goal is not to look stylish but to show respect to the court.  You do not need to buy a new suit or dress but you should dress up.  Do not wear a lot of jewelry or expensive items. 

In family court, try and avoid bringing young children.   Bringing support is a good thing but be careful about significant others, particularly if no it involves an ex.  You generally can not bring a friend or relative with you while negotiating or when in front of the judge.

Make sure to arrive Early for court to find parking and to wait in line for a metal detector.  Expect to be waiting in court for a while.