You should do some research on the company you are interviewing for so you have a general idea of at least what they do and can make banter about it with the person who is interviewing you. Not too much though because the person will also want to boast about the success of the company.
You should also bring a copy of your resume if you have one. Also bring your references and phone numbers!
Dress nicely of course and comb your hair neatly! What you look like has a huge impact, sometimes as much so as your experience.
The best thing that has already been said is to be confident and don't come off as if you desperately need the job. If you go in with that mentality you will be much calmer.
Also as has been said I would definitely say to do a few interviews for jobs you may not even want or be overqualified for just to get the experience if you don't have much.
Show up early not by more than 15 mins. The person interviewing you may have other things scheduled but the 15 mins can give you time to fill out any papers or applications if they are requiring that.
Can you tell I work in Human Resources?
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