Summarize this article:

Once the focal point is arranged, you'll want to add some seating to the room (unless, perhaps, it is a bedroom). Make sure the seating you choose is the right size for the room. Leaving enough space, as with the focal point, to make it usable. For example, at least three feet should be available behind each dining chair.  Try to limit yourself to only one piece of oversized furniture in a single room. Too many and it will look crowded and cheap. When you arrange the seating in the room, it should appear open and inviting when standing at the entrance to the room (or at least the main entrance). Avoid having chairs facing away from the door, for example. You can add drama to a room by placing furniture at an angle, but be careful. This takes up valuable space in a small room. Use furniture placed at angles only if your room is very large or you don't quite have enough furniture to fill the space. When place seating in an area that will be used for conversation, such as living room furniture, you should be careful not to put the items too far apart or too close together. Roughly 6–8 feet (1.8–2.4 m) for seating pieces facing each other is a good rule of thumb. Pieces places in an L shape should have 6"-1' between their corners.

Summary:
Scale your seating. Create an open arrangement. Use angles strategically. Distance the furniture appropriately.