I was sort of the guide and when we were on the bus/monorail... I would look at some of the clues for where HM were and sort of prep the kids. "OK as we walk into Epcot/AK... there are 3 HM before the Oasis... I gave them hints and didn't tell them the actual spot. If someone found one they would get the credit and I took a picture of the HM if I could. Sometimes we were moving and it was not possible. I also gave hints as we were waiting in lines.
Keep sticky notes in the book to keep your places and keep score w/ the clue #, who got it, and points awarded.
We weren't die hard players, just killed time and it helped the kids see more details of the parks.
Have fun!