Dress nice & casual. Don't over dress, no holes or t-shirts, tuck your shirt in. Casual shoes, stay away from sneakers. Look, nice.
Take a pen with you to show you are prepared.
Be calm, don't be nervous. Don't give out too much info, keep your answers short but intelligent. Think ahead of time a question you can ask them.( They will ask if you have any Q's.)
Look the interviewer in the eye, keep eye contact. Be pleasent & show an interest in the job. Let them know that your available to start a.s.a.p. and be reliable.