I cannot stress being overly polite, no matter whom you speak with, weather it be in person, over the telephone, or email. You may not understand the person on the phone sometimes, have them repeat themselves so that each detail of what they are asking you is clear. If you happen to meet someone in person, Thank them for their time as they could be busy doing something else, it doesn't matter if this is someone in air freight.
Follow up Thank you: Take this with a grain of salt, your fate is usually sealed when you leave the simulator or interview. If sending a Thank you letter by regular mail, it will cross paths with your rejection letter at the post office. If you are hired, the invitation is usually by telephone. With more hiring going through cyber space, a Thank you email is always in order.