Gleanings from a Sept. 2015 Family Tree Magazine, NEHGS e-newsletters and my own research.
Tombstones at military cemeteries are in uniform lines. The emblems on them are not all Christian crosses, Stars of David or the Islam crescent and star. The National Cemetery Administration has a list of 65 emblems that may be found on the headstones for atheists, wiccans and others. Those emblems could be useful clues.
The Netherlands American Cemetery in Margraten contains 8,301 American servicemen. The Dutch go to each grave several times a year, especially on Memorial Day. They place flowers, clean, and report any issues with the grave. Some graves have been tended by the same Dutch family for 4 generations. There is a waiting list of 300 people to adopt a grave. What a way to show their appreciation.