For World War I to the present-try to find Interent Veterans Associations of the regiments/ships/Figther and or Bomber Squadrons/Groups in which your relations served. Then try to inquire if there are any photographs of units your relation served with
To find out at least for what units your relatives served in from the
Civil War to World War II write to the State Adjutant General's office
in the State Capital of the State where relation was residing at time of
enlistment.