Dream Signs:
People - There always seem to be a large number of people in my dreams. There are occasional times where I and/or the focus character are alone or with a few people, but more often than not, there are always people around.
Large open spaces - 'm rarely in a normal-sized room. Typically I am either outside, or in a room that is larger than it has a right to be. I never spend much time there if I am in a small area.
Those are my two consistent dream signs. All others seem to change just before or not long after I discover what they are. I've thought about attempting to create a DS, but no luck so far. Further persistence may be required.