Do not be fearful to declare you don't know an answer.
Do not go off topic. Keep your thoughts on the things you are good at.
Put on a clean suit. Wear it sharp and neat.
Be sincere, optimistic, focused, positive, frank and succint.
Say thank you to your interviewer at the end and after by email or send a 'thank you' card by post.
Think of body language like not playing with a pen, sitting upright, not slouching and speaking clearly.
Suggestions for those looking for employment:
"Be sure to develop all the materials that you will need in filling out an employment application in advance. Even if you are supplying a CV, it is possible that you will also need to complete a standard application for the human resources department."