A large part of debate is doing research and gathering evidence to support your arguments. While it may seem like a daunting task at first, over time doing research will become second nature and it is really necessary.
What constitutes good Evidence?
While you can find all sorts of quotes in support of a premise, certain sources will inevitably be better than others. It's necessary to gather evidence first because you always want to capitalize on the prestige of somebody important who has made the argument before you and second because they can probably say it better than you can.
Type of Source
The first way to determine whether a source is a good one to use for evidence is to consider where it comes from. Newspapers, articles, studies, and academic references are in general good sources because they come from a peer-reviewed body of work that has been ensured to be of sufficiently high quality. Good places to look for such articles are Google Scholar or Lexis Nexis.
Places that you should not cite as evidence are personal websites or blogs. In general, the language tends to be less professional and because there is no peer review process, there is no guaranteeing that facts they cite are actually true. Note: this holds true even if it happens to be the personal blog of a well-known member in the appropriate field. Because it is there personal site, there is no way to hold them accountable for what they say.
Another important thing worth considering are the qualifications of the author you are citing. Normally, this doesn't end up being too much of an issue. Most published works are written by qualified authors, but there are a few notable exceptions. One thing to make sure of is that the author you cite has a degree in a relevant field. If you're citing an economics professor who is discussing the chemical side-effects of dumping sewage waste, then that professor probably isn't qualified.
Besides simply what a person's formal academic background is or where they went to school, it's also worthwhile to consider other positions they may occupy. For example, if that same professor was on the board of the Chemical Waste Aftereffects Committee, she may in fact be very qualified. One thing to keep in mind though is that even though you can compare your evidence on the basis of the competency of your sources, in general it is not effective to directly compare the schools where the two authors are employed. For example, just because one professor works at Harvard while the other works at UC Santa Barbara, it does not directly follow that one is more qualified than the other.
Further, a good way to determine whether a source is good is to see when it was published. This is especially valuable when discussing current events or things that can vary wildly from day to day, like politics. While in general, recent is better that isn't always the case. If you want to make an argument regarding the efficacy of nuclear deterrence during the Cold War, it shouldn't matter too much whether your article is from 2005 or 2011. You should pay attention to recency only when it is likely that some event in the intervening time period may have sparked a change that would affect your argument.
How to "Cut Cards"
What exactly is a card?
A card is another name for a short piece of evidence, and the name is leftover from the days of yore when quotes used as evidence were handwritten on index cards. When it comes to gathering evidence, it takes more than just finding a good quote that backs up your claim. You also have to selectively edit out words and phrases that don't add to your argument while at the same time preserving the original meaning of the passage.
While it may seem foreign, this practice is widely accepted because of the benefits it has. Though six minutes may seem like to an eternity for you initially, it really is a very limited time slot during which you can present your arguments. Thus, the more concise your arguments can be, while still preserving their meaning, the more arguments you can provide in defense of your position.
In selectively editing out words, it is important not to just delete them but to instead either reduce their size or put all other words in boldface. This is a precaution taken to ensure that you are accurately representing the evidence and not editing it in such a way as to alter its meaning. Below is an example of a card (where bolded words represent edited out, also known as "lined down," parts of the card):
The United States has two sorts of sanctions in its arsenal: trade and economic. Trade sanctions remove what the government calls "preference programs"--basic privileges, like Most Favored Nation trade status or Import-Export Bank loans, given to all friendly countries. The United States has imposed trade sanctions on nations that, for example, close their markets to its goods (China), sell arms to hostile regimes (Pakistan), and violate human rights (Myanmar). Trade sanctions are reprimands, tailored to reform a sanctioned country's behavior without completely alienating it. If trade sanctions fail, the president can adopt the more draconian economic sanctions, which do aim to alienate. Economic sanctions can include trade embargoes, bans on cash transfers and loans from American financial institutions, and measures that prevent access to American assets. Because economic sanctions can strangle an economy, they are considered one step shy of war. Indeed, it has become almost a diplomatic necessity to level sanctions prior to military intervention, to show that all other options have been exhausted.
Citation: Franklin Foer [Franklin Foer is a senior editor at the New Republic and a contributing editor at New York]. “Economic Sanctions”. Slate. 9/14/96.
For more card examples, including more formatted, competition-ready examples, please see any of the downloadable files on this site.
An important part of cutting cards is to also have citations. No citation style in necessary is required, but it is important to have relevant information which includes:
If you have other relevant information, you should include it as well. The purpose of the citation is to allow someone to find the source again and verify that it said what you said it said. Further, an important thing to include if you can is author qualifications. Giving some background about the author and her experience in the field is a good way to cover your bases if someone thinks that your source is suspect.