It is a good question, I would really suggest you the following:
1- BE ON TIME, don't come late.
2-You should be yourself (relax), because if you were uncomfortable this would create a wrong impression.
3- Physical appearance matters, especially at the first time...
4-Keep a smile on your face..
i think you need to read more about this matter, but in my opinion, these are the main points.
Good Luck
Glance of an employee at first:
1. Punctuality.
2. Interview Requirements:
3. Neat and Professional Dressing.
4. Enthusiasm about the company.
5. Be confident, Patient, Keep an eye contact with a little smile and a trust worthy candidate.