Your body language says more about  you to the interviewer rather than what you are saying from  your mouth. .

The following are the important points:- 

1. Waiting for the Interview.
2. Walking inside the interview room. (Entering)
3. Sitting in the chair.
4. Body gestures during conversation with the interviewer.
5. Eye movements
6. Leaving the interview.

1) Waiting for the Interview
    

• Never look out when two people are debating.  This shows that you are a follower of the two.  If you can converse with them

• Sit relaxed

     Converse with the near ones and talk a good constructive topic.  This shows that you are friendly to your environment.

• Never talk in such a way that creates a high heart beat situation.
  
  2) Walking inside the interview room. (Entering)
  
       This is the first thing we do in the interview.  The things which includes in this steps are  

• Seeking permission to enter the interview room and Walking inside it, 
• Standing and Seeking permission to sit in the chair

 Seeking permission to enter into the interview room:-  While asking permission, Ask with a good tone, rather not too higher or too lower.  Ask confidently, May I come in Sir/Madam or Shall i come in Sir/madam.   After getting permission walk into the room.

Walking:-  While walking into the interview room, walk with head held high and upraised chest and shoulders.  This shows your confidence level.  Since if you walk with your head focusing on the ground means, it shows that you are thinking, nervous, panic about the interview.  So the interviewer expects to walk with confidence.  Also have a note that while walking don’t look in an arrogancy manner. 
Don’t  enter your hands into your pant pocket, leave it free and walk, this shows that you want to be secured.
Don’t alter your shirt buttons, wrist watches or anything.  This shows that you are nervous.
Don’t see the time before entering the into interview, if you know that your interviewer is watching you.