Tomas is right, dress as nice as possible.
Also, don't make anything up. Just admit you're wrong and show remorse for your actions.
My personal experience, I got caught doing 87 in a 65
on a rainy day. I worked for a car dealership at the time and I was driving with a dealer's plate. Well, the plate that I happen to have been using had 4 or 5 DUIs on it. To add salt to the wound, I didn't have the insurance card through my work and I didn't have the license plate where it was supposed to be because I was driving a brand new Chevy Cavalier and the plate kit wasn't installed yet.
Well, I went to court to fight the four tickets the state trooper gave me. To my surprise, the cop actually showed up. He got to talk first and he gave a 5 to 10 minute speach on how his radar gun is damn near flawless when its rainy because I guess he thought I was going to argue that.
All I did was said I was sorry. I explained that it was a dealers plate and I was unaware of the prior DUIs on it. I also had a letter drawn up from the owner of my dealership stating that I was a good worker and that I was following what I was told with the license plate. I claimed that I straight up forgot the proof of insurance in the copier and I also had the salesman who I was driving for there. He was pressuring me to get back fast so that he could sell the car.
She dropped all of the charges except the speeding, she declined it to the bare minimum, no points and a small fine.