* Think outside the box. For example, if "Duck" is on your list, it could
  refer to a rubber ducky, a wooden carving of a duck, or a roast duck on
  someone's dinner plate Visit the salon at regular intervals during an 
  investigation. Sometimes finding new clues will open up new questions
  for Poirot to ask. 

* All of the items to find are historically accurate to the early 20th-
  century time period in which the book took place, which requires a bit of
  an adjustment in thinking. For example, if "car" is on your list of items
  to find, you should be looking for an old-fashioned Model T Ford type of 
  vehicle; if you're looking for a music stand, expect to see an old ornate
  wooden one instead of the black metal variety; and a bathing suit will be
  a modest black affair, not a sexy bikini!