First impressions are very important. They help the interviewer decide whether he or she wants to hire you or not.
Your Appearance
Dress in clothes you would wear on the job. Wear conservative colors and avoid flashy fashions. Avoid too much jewelry or strong scents.
Body Language
Stand up very straight. Do not exhibit nervous gestures by tapping your feet, drumming your fingers, twisting your hair, rocking in your chair, crossing and re-crossing your legs, etc. Take pride in who you are what you offer.
If you will follow this advice, you will ace your interview and soon be cashing big checks.