For a meeting with your child's teacher to be productive, enter the meeting already possessing a firm grasp on your child's academic progress. Regular discuss how school is going with your child and ask to see his grades as he receives to minimize the likelihood you will be blindsided at a meeting with news that he is struggling on tests or not completing assignments.
Prior to your meeting, take time to review the information you have gathered from speaking to your child and identify areas you are pleased with and areas that concern you. Read over the syllabus for the course to note areas where your child struggled and future areas you worry may be a problem later in the school year. Write notes to ensure you do not forget to bring up topics you consider to be important to discuss with the teacher.
Asking about your child's progress, as well as areas where the teacher feels your child is excelling and struggling, shows that you are engaged in the meeting. Respond to statements made by the teacher with questions that build off what has previously been said to establish that you are listening and doing your best to work with the teacher. Establishing a symbiotic relationship will help to engender good will with the teacher.
Maintaining the right attitude can mean the difference between a productive meeting with a teacher and a meeting which wastes both parties' time. While it is not required that you agree with everything the teacher says, remember that ultimately you both have a goal of getting your child to succeed as much as possible in the class. It makes your life and the teacher's life easier to have a successful student. Clearly state your points of contention, but be sure not to phrase them as accusations, such as blaming the teacher for your child's errors, and do not get defensive in return when the teacher disagrees with you.