Knowing information about the topic you’re about to write about is very important. Having a sense of what you’ll be covering is a good way to have an idea of how to write your paper. Reading previous stories, documents and even official websites is a good start to do research on the topic. I agree with Filak on that. Getting facts ahead of time before an interview or on scene coverage is important because it may help you ask the person more questions or help you focus on one part of the topic you may want to focus on.
Reading about how to keep your beat in reporting is very helpful. I think reading about your interviewee before you interview them would be helpful to keep your conversation going. If it is a topic about an environment or something, still doing research on the area of topic would still be helpful in my opinion.