Congrats on landing an interview! I would suggest going over some practice interview questions ahead of time (seeing as you said they can make you nervous). A couple of good websites with recommendations are...
Nurse Interview Questions and Answers
10 Worst Answers to Nursing Interview Questions - Nursing Link
Dress professionally, ie: minimal makeup, bare nails, close-toed shoes, basically dress conservatively. First impressions really do mean a lot. Make sure to enunciate your words, and if you can't think of an answer to a question don't be afraid to pause for a few seconds. It is better than "and...um...uh...." :)
Interview Tips | How To Nail An Interview (20 Tips) - 2010
Make sure to act very polite and professional, but also be like-able. I have found that the worst employees manage to keep their jobs because their managers "like" them personally :/
I usually carry all my documents in a manila folder. I will bring my resume, fingerprint card, license, bls card, and any other nursing related awards or training certificates.
Also, make sure you tell the manager or HR person what they want to hear. You are applying for a job that involves you working with people, so let them know that you love being around people, are a team player, empathetic, etc.
Good luck! You have plenty of time to practice and I'm sure you will do fine!