My dear Vidita,
Your question itself shows as to how serious you are about the presentation. Such seriousness in fact would make you perform well and at the same time may make you feel nervous also, when you give room too much for precautions/preparations.
A good performance is always based on two things. (1) How broader and deeper your knowledge base is and (2) how cooly and boldly you deliver it. Normally those who are intelligent seldom delivers good.
Your self confidence (more so when you are good in your subject) plays the miracle. I always compare this to a flight taking off. First few minutes (the time depends upon how much time is given to you) should be taken to impress the crowd - this is just like a flight taking the momentum to lift in the air. The slowly and steadily one has to take the heights and speed. Hover around several rounds and then slowly and steadily land to have a safe halt.
Your body langauge should such that the gathering likes you and comes into your fold so comfortably and easily. The quicker the acceptance the more the listening.
Hope this is enough for you for the moment.
All the Best,
Ganesh.R. - Manager (Admn.), DCW Limited.
Freelance Soft Skill Trainer, Reiki Master, Hypno Theraphist and Psychological Counseller.