Body language:
The body language plays a very important role in an interview. This implies that when one makes any positive statements, those movements should be supported by his/her body language. When entering the interview room, one should not have a tough look and a smile with tension in mind. Even the way one enters the room and sits is noticed. Actually one should enter with a calm smile on face and a stiff body posture which shows that he/she is not nervous at all and has a positive friendly attitude.This makes the interviewer also to feel open and become friendly at the first sight which in return increases one’s chances to get through the interview.

Punctuality:
It is very important to be on time for an interview. Instead, one should reach an hour early which is much better than arriving a few minutes late and will put a bad impression on the interviewrs. Also, if one reaches early, he/she gets enough time to relax your mind, put all the scattered thoughts in the mind together, get used to the environment and lessen the nervousness. Moreover, it gives time to one to have a final check on yourself.

Greet the Interviewers:
‘The first impression is the last impression” is one of the oldest and important idiom used by us. As and when one enters the room for interview, everybody looks at his/her personality, facial expressions and that is the time when the interviewer has the first impression about you. Therefore, one should greet the interviewers by taking his/her last name and if one does not know their names, one should first check it on the reception before going in the interview room.

Handshake:
I know that most of us do not consider or are unknown that the way you shake hands with the interviewer also plays a very important part in an interview. To form a positive impression one should do a firm handshake, which shows his/her confidence level. Also, when one is shaking hands, one should make eye contact with the person he/she is shaking hands with.
If one gives a weak handshake that shows that he/she is weak and not confident enough to take up the responsibilities at work. Also, if the handshake is too hard and by chance it hurts the interviewer a little, it puts an impression that he/she is Dominant.
One should shake hands for 3-5 seconds maximum.

Maintain Eye contact:
One should try to make an eye contact with the interviewer especially when you are having any conversation with the interviewer. If one tries to avoid the eye contact, this makes the interviewer believe that there is something fishy and he/she is hiding something. Hence, that gives them an impression that the interviewee is unfaithful or untrustworthy.
Therefore, one should be confidently talking with the interviewer with proper eye contact. But that does not at all mean that one should stare at the interviewer.

Way you Sit:
I understand that it sounds a little different but yes the way one sits in the interview room and when do you sit also shows your many things about your personality.
One should not sit immediately after entering the interview room but wait for the interviewer to offer him/her a seat. If not offered a seat by the interviewer, one should take permission to take a seat. This is because if one sits without being offered or without asking, that makes the interviewer perceive that he/she is arrogant, over-confident, nervous, etc. which can act against you in the interview.

Talk Precisely:
One should be precise on what he/she is talking as the rule says that the interviewee should talk 1/3rd of the time. One should let the interviewer talk at the beginning about what are the requirements, about the company details, what job profile are they looking for, how they want their employees to be in the organization,etc. One should always keep in mind that when the interviewer is doing the above talk, he/she should not at all be giving a negative message by their body language instead he/she should have a positive body language towards whatever the interviewer explains and it is much more beneficial for the interviewee to ask questions to show that he/she is quite interested to know more about the organization. It is much better than only speaking about yourself continuously.

Be Confident at the End:
At the end of the interview also, one should be energetic and should have a firm and energetic handshake before leaving the interview room. One should also thank the interviewer as well at the same time while shaking hands before leaving in the same way as done when entered the room athis gives an impression that you are friendly and also leaves a good impression on the interviewers. One should not get up from the seat and show hurry in leaving the room at the end. Instead, he/she should wait for the interviewer to show that it is over now.
Even if one thinks that the interview did not go well and he/she is sure that he/she may get rejected 99.9% , still one should never let them get the impression that he/she is discouraged sthe reaction.

Thanking:
One of the most essential part is thanking the interviewer at the end for their time and also sending a small ‘thank you’ mail after leaving the same day. In this mail one can write precisely the important parts of the conversation at the time of interview and again emphasize on your skills which can bring benefits to the organization and the position you have applied for.