Follow the rules in court.
When you arrive in any court, the norm is for the Judge or bailiff to give some ground rules. Security is a major issue in all courts, so I am appreciative of scanners in every courthouse. Some courts don't have any screening before you enter, and in this day and age I think that's a mistake.
Some courts are pretty hard core about courtroom etiquette. The bailiff will bark at you if you talk to your courtroom neighbor, look at your phone and if your phone starts beeping, look out. Other courts have a more relaxed atmosphere. Some judges will allow you to use your phone or other devices so long as it's quite.
Whatever the rules are, it is in your best interest to follow them. If the Judge or bailiff tells you not to bring your purse/bag to the Judge's bench, don't do it. If the Judge tells you not to stick papers or documents in his/her face, don't do it. Some courts have somewhat of a sense of humor with people that have a hard time following rules. Others will find you in contempt and you can get arrested. The failure to follow the court's rules in all likelihood will not benefit your case.
Typically it's not a good idea to interrupt anyone, but especially not a Judge in court. Manners. Manners. Manners. At the end of the day, you will have a more pleasant experience in any court if you follow basic manners.