What are the body language expressions that must be avoided during an interview?

Staring only towards one place/person

Changing postures frequently

changing voice pitch too loud or too low

Reflexes like tapping, shuffling fingers, rubbing nose, etc

Cutting interviewers' statement in between

laughing or smiling abruptly

yawning 

Being confident is somthing that is required, over confident is something that has to be strongly avoided, answer a question when been asked is something that add weightage to your answer, saying everything when not been asked creates a reverse effect.