Getting ready for an interview will always be a nervous feeling. Your mind get flooded with different questions, for instance, what they would ask, would you manage to answer them, would you get the job and so on. It's a common problem; one needs to take care of few things before heading to a job interview.
It's good to have a handful of knowledge about the company. Study the company website, know its goals, missions and history. You may face a lot of questions about what and why you want to join a specific organization. So it's good to be ready to answer most of the questions with a confident face.