When preparing for debate, the first step is to define the terms of the resolution. Dictionaries and encyclopedias will help you find the most precise definitions possible. Start first with a general dictionary and then move to one that is more specific to your topic.
General dictionaries will provide you with common definitions, but for academic debate, you need to discover and use specialized definitions, which can be found in specialized dictioaries. Specialized dictionaries are used by experts (which is what you are becoming!) to help form a precise understanding of the temrs used in a given controversy.