Research your topic to prepare both your talking points and your counterpoints to likely arguments. Decide how you want to respond to arguments claiming that television violence negatively affects children. A likely argument you'll want to make in your favor is the amount of advertising revenue brought in from violent programming such as "24," "World Wrestling Entertainment" and the "Ultimate Fighting Championship," and how this stimulates the economy.
Prepare notes. Note cards will probably be more effective than paper because they are sturdier and more easily concealed. Keep your notes concise and to the point. Split them into your own talking points for television violence and the counters to what you feel your opposition will be arguing. Each study that you want to cite should have its own card. Slate reported a study done by economists Matthew Gentzkow and Jesse Shapiro at the University of Chicago that disputes the television/violent children correlation and points out flaws in most of the previous studies regarding how they were conducted and provides an effective counterpoint. This information should be isolated on its own index card.
Answer questions directly and without a lot of other issues added in. If you are asked about studies showing violent television leads to violent kids, you can respond with alternate studies showing differently (such as the Slate article) or possibly discuss the role of parenting in counteracting any such tendencies. Talking about the media's right to freedom of speech would be a separate talking point unrelated to the question at hand and answering with that would make you look like you are dodging the question. Also, correlation does not imply cause and effect. It is also possible that children with a predisposition for violence are more attracted to violent programming on TV. This provides an effective counterpoint.
Write a strong closing argument. Finish your debate with a summary of your main talking points (such as economic benefit or the role of parents limiting children's access to TV programming) and close with a concise statement that sums up your end goal in the debate, whether that be to stop a media restriction or to dispute a recent study.