Reading primary sources would be helpful background if you have the time, but if I wanted to compare two cars I would look at their real world performance and reliability. So if I was comparing socialism and capitalism I would compare the two in action, not in theory. Now if your debate is anything at all like a typical debate it will probably an exercise in futility as there will be no agreed upon definition of what exactly socialism or capitalism is in practice and so it will be very difficult to compare the two. This problem might be solved by getting an agreed upon definition of the terms prior to the debate, but this might prove impossible. So instead you could go into the debate and instead demonstrate how futile the debate is by showing how on the definition you use puts countries most people assume are capitalist into the socialist group or countries that most peple assume are socialist into the capitalist group. A crude measure such as defining a socialist country as one in which the government collects more than 50% of GDP in taxes is better than nothing. This is crude because it ignores how much "wealth" is held by the public sector.