Debating shouldn't involve personal emotions as Midnight shadow noted, debating is a healthy thing to do. It shouldn't be seen and/or mistaken as a verbal fight club.
My advice: Be well prepared from time to time and keep on learning.
Practice a good reading habit! Read more materials, from news articles to books, or even materials published by a person you are not fond of (to expose yourself to different views). While not a necessity, it would be great if you can recall the materials' title for citations in the future.
Learn about the topic, learning doesn't necessarily mean cramming the information. When you are engaged in a debate, you can't just simply emphasize your own views and points; You should, at least, need to know the opposition's (basic yet detailed) ideas and points. It's kind of like lawyers' in court -- when the prosecution brings up an Article, the attorney should have a basic idea what the Article is about. Therefore, it is important to learn about the topic and to absorb knowledge.