Good research is critical to a successful persuasive essay. You must have content to back up your claims. Your claims must in turn be well documented and elaborated. Be careful to take detailed notes as you record information that documents both sides of your issue. You will be referring to these notes as you begin to draft your paper.
You can find facts from a variety of different resources: encyclopedias, newspapers, magazines, textbooks, online interviews, public documents, and face-to-face interviews.
Once your research is complete, you'll want to begin thinking through your process of persuasion.