The Three “F’s”– Function, Focal Point and Flow Considerations
Function – What kind of room is it? Arranging furniture in a dining room is much different than in a living room, bedroom or office. Does the room need to accommodate a lot of people or just a few?
Focal Point – What do you want to emphasize? If you have a big bay window that looks out over a scenic vista, perhaps you want to highlight the view. Maybe your pride and joy is a majestic decorative fireplace. Orient your furniture to direct attention to the focal point. If viewing a widescreen HD television is important to you, the optimal distance between the TV set and any seating is roughly three times the size of the screen.
Flow – Can people move easily from place to place? Notice at how people enter and exit the room, and how doors open and close. Cluttered pathways can make you feel like you’re in a pinball machine, so avoid placing large pieces of furniture in the natural lane of traffic if at all possible. Allow at least 3 feet of open space for your primary traffic routes
(source: "Tricks of the Trade: Furniture Arranging and Interior Design Tips" by Bill Ferris)