DC Ruins posts are for any areas outside settlements (ie. Subways, buildings, etc...) that fall within the city boundaries.
When starting a new topic in the Ruins decide if you want to be near any land marks or if you're just out wandering and taking in the sights. Titles can be whatever you want them to be (with extra points for creativity) but if you're near a location it helps to put it in the name, either directly or in brackets after the title. (ie. "Vacationing in Evergreen Mills" or "Raider Rack-em-up. (Evergreen Mills)" etc...)
If you're planning on a battle heavy topic that should also be mentioned in the title. Some players may not be interested in fighting, and once you're in a fire-fight it's hard to write your way out of it. Putting (Combat Heavy) after the title is a good way of warning others what they're getting into.