A poker look on your face conveys a too serious, contemplative persona. No list of tips on nonverbal communication would be complete without the mention of maintaining good eye contact. It is a balancing act. Try shifting your eyes back and forth between the other person's two eyes, slowly. They imply that you may be nervous, impatient or bored.
Good grooming is essential to projecting the proper image.
There is no excuse for cutting corners when it comes to personal grooming and hygiene. Good grooming shows that you care enough about yourself and about the interview to make an effort. Clean fingernails and use hand cream for dryness. Take a bath. Have a neatly trimmed, fresh haircut.