I hope your resume is no longer than 1 page. You need to get the attention.
Stand up straight, never lean forward unless you did not hear the question. Speak slowly with confidence. If you don't know what to do with your hands hold your fingertips together. Look in the eye of the interviewer. Don't look at the ceiling when answering.
Don't overdress for the position you're looking for.
Never admit that you don't know the answer.
"No sir, I have not had any experience with this particular ________, but I like challenge and will always find the right way to accomplish the task successfully.