sitting still, shaking their hand as you approach them, not running on and on about one thing, replying with a yes ma'am no ma'am or yes sir no sir. making sure that your hair is out of you face and nice and neat so that you don't have to keep fixing it. and that you are dressed to impress with nice clothes that are clean and pressed tapping your feet, and don't use umm or uhh it makes you look unprepared and silly. don't use one word to many times it will seem like you have a limited vocabulary.
hope this helps .