In the various apartments we've inhabited over the years, we've often had to make do with a single central room, which triples as a living room, dining room and playroom for the kiddos. The problem is, when the kids scatter toys across the floor, that means your living room and dining room are also trashed.
One way to help limit this is by segmenting the room, or creating zones. This can look as simple as keeping your couch and TV on one side of the room and your chair and bookshelf on the other. Or you can arrange your furniture to help arrange the room in more elaborate ways.
The idea is, if you're using one zone -- say, the TV area -- you can tidy it up more easily before transitioning elsewhere, keeping the room in general shape even as you move around and use different areas. In addition, this strategy just makes it easier to cohabitate with others in a small space.