First, DO NOT be on time. Be there 30 minutes AHEAD of time. Court is stressful and you don’t need to worry of being late, going to the wrong courtroom, not being able to talk to the attorney in advance, etc. Also, make sure you know precisely the court you are headed to (e.g., the address, the particular court number or name, etc.) and clear this up before the day of your appearance. By the way, if your attorney is to go to court with you and that person has never taken the time to meet you before this - be wary. Our experience is that attorneys like this are not adequately prepared.
Second, be polite. Turn your phone off or it might get confiscated, and don’t use foul language. Dress like you are going to a job interview or a contemporary church service. (Tip from past experience: Witnesses testifying with pictures or words regarding illegal drugs or anarchy groups emblazoned on their T-shirts usually are not well-received by the judge or the jury.) Follow the directions of the bailiff - he or she is in charge of the court and is second only to the judge. Just about every bailiff will be good to you if you are good to him or her.
Third, take with you anything that you think might be relevant to the case. This can include pictures, drawings, memos, bills, and recordings. Obviously, if you have an attorney, all of this should be planned out in advance and each of these items should be identified and prepared. However, if the occasion is such that you do not have an attorney, just ask yourself in advance what it is that you have to tell or show the court that is relevant (e.g., would make a difference for the issue being decided).
Fourth, get to the point. If the judge asks you where you were when the car ran the red light and you find yourself telling her about the time in the third grade when you won the soap box derby, rein it in! Believe me, judges have heard it all but they don’t need to hear it ALL when you take the stand. As a general rule, I tell witnesses to give answers of no more than 3 sentence. Let the attorney or judge ask more questions if more information is needed. If you’ve really got something that hasn’t been covered which you think is vital to the case, make your point. If it’s good, most likely the judge won’t react, one attorney will smile and the other one will look like they just received an extra tax bill. If it’s a bomb, the judge will probably let you know quickly. Some are relatively polite but, be forewarned: if you see the carotid artery of your judge’s neck for the first time, it is time to reel it in and start listening more closely.
Fifth, if you’re not sure what happened, find out when court is over. You usually can learn from one of the lawyers or that bailiff you made friends with….