Congratulations!!!!
I like what the others above have posted. Many times they will ask if you have any questions. It would be good to show your interest if you can have a prepared question or two something about what the company or job that you could not find in researching it (not about pay or benefits, but the company/job itself) or what do they consider a successful candidate to be, etc.
Dress the part of the position you are looking or business attire for as they can then they can see you better in the role of what they are hiring you for and know you are serious, yet do smile once in awhile.
Deep breaths and Wishing you the very best of luck!!!!