Nothing! Rule number one is to never admit guilt. This doesn't mean you have to be rude to the officer. It simply means that if the officer asks you ANYTHING, simply state that you are "invoking your right to remain silent," and provide the officer your driver's license, registration, and insurance info. Too many people think they can talk their way out of a ticket, and end up sinking their case at trial by inadvertently making an admission of guilt.
Keep in mind that when you are stopped for a routine traffic stop, police do NOT need to read you your Miranda rights in order to use your statements against you at trial.