1) Arrive on time.

2) Be courteous.

3) Be yourself; don't pretend to be the "ideal candidate"; interviewers can tell the difference.

4) Never ever use the "pictures of you mother" joke during the interview.

- Dress professionally, befitting of a formal interview. Be well-groomed and neat.
- Arrive about 10 minutes early. This gives you some time to collect yourself and be calm for the interview.
- Greet your interviewer(s) politely and don't forget to smile!
- Give a good, firm handshake (two shakes). This gives the impression of confidence. But don't grip and shake too hard!
- Appear enthusiastic about joining the company (lean <em>very</em> slightly forward during the interview, have an interested expression, etc.), but do not be <em>overly</em> enthusiastic!
- Body language is important. Do not cross your legs. Do not fiddle with anything. Keep your hands and legs still.
- Try to be as genuine as possible. Be yourself, your professional self.
- Try not to be nervous. Don't use "fillers" in your speech (e.g. "uhh", "umm", "you know")
- Don't try to crack jokes. You do not know the interviewer's sense of humour and he might take offense.
- Be prepared beforehand to answer questions that interviewers commonly ask, such as "why did you leave your previous job?" (to which you should not answer negatively like "my previous boss was a jerk"), "why do you want to join our company?", etc.
- When the interview is over, wait for him to stand before standing up yourself (unless he's not going to stand and is sending you out the room without showing you out), but do not wait too long to stand after he stands. Shake the interviewer's hand and thank him for the opportunity and his time. Give a slight nod to him while thanking him.

Good luck! 

1) Dress nicely and exhibit good grooming (i.e. shower beforehand).

What kind of audience are you writing this for?  Which country/countries and which profession?

I think #1 will help regardless.

don't : 

1 talk badly bout your last job

2 show that u in a strong need for this job

3 stand up until the interviewer finish the meeting

4 laugh too loudly