When you are finished with your soup, if there is a service plate underneath your soup bowl or cup, leave the soup spoon on this plate, to the right of the soup bowl or cup. If there is no plate underneath, leave the soup spoon in the bowl or cup with the handle at about four o'clock.
If you would like to get those last few delicious drops of soup, you may tip the soup bowl or cup slightly away from you and scoop away. You may not lift the bowl or cup to your face and drink from it. (We know you do that with your cereal bowl in the privacy of your own home when nobody is looking -- that can just be our little secret.)
Exceptions to the ban on soup cup lifting: a boullion cup, which is lifted by the handles and some cultures that drink soup from the cup. Important reminder: always learn the meeting, greeting and eating customs of other cultures you will be dealing with, whether you visit their country or they visit yours.
Thank you to our colleagues at the Culture & Manners Institute for sharing their insight!