Body language is instinctually read by others in order to interpret what you are saying.
Here are a couple of things to avoid–
Fidget with pen, fingers or ring – looks like you are nervous or unsure of yourself
Licking your lips – looks like you are chomping on the bit or bored
Sloped shoulders – looks like you are defeat
Breaking eye contact – looks like you are unsure
To be seen as confident you want to make sure that you use body language that shows your positive strength.