I have worked at top banks and companies for over 15 years and have been running a recruitment outfit for over 6 years now. So, I would like to give some practical tips for youngsters who are appearing for job interviews:
Do homework about the client: Perhaps this is the single most important point. Please spend a day or two researching about the company and industry. Many of the candidates get rejected because they are not adequately prepared.
Dress Properly: Proper dress gives a very good impression to the client officials. Improper dress gives the impression of being casual and careless.
Dont be late: If you have been assigned some particaular time for the interview, please be on time. Being late can ruin your chances.
I hope these tips help you in your interviews.