I always used to tackle it by taking the holes one by one, starting with the one in the NW and going clockwise. I took some damage early on, but I found some amber reasonably quickly, although not enough to protect the whole party for quite some time. I never worked out which underground sections of which holes interconnected, so I ended up going over some ground twice or three times, but I preferred doing that to running the risk of leaving sections unvisited.Scoring high as the game reckons it is not important to me. My aim when I play these games is to go everywhere I can reach, and do everything I can. For example, you can climb some of the mountains in MM9. I've never found anything up these, but there's always hope that I might! Also, there is a way to explore most of the mountains on the Isle of Fire in MM3. There's nothing there, but I enjoyed finding a way to do it.
So I always end up with a miserably low score, but I've had great fun getting it.