What is a focal point? It's a place in the room where your eye is drawn. It's a place around which you'll place your furniture (or at least be mindful of when placing furniture.) A focal point can give the room a purpose.
In the living room, the focal point is almost always the fireplace. Your seating arrangement should be oriented with this in mind. Here are two popular arrangements that work well: 1) The sofa faces the fireplace and two chairs flank the fireplace and face the sofa (see photo); 2) The sofa runs perpendicular to the fireplace and two chairs sit opposite and face the sofa.
I said the living room's focal point is "usually" the fireplace (because if its architecture, your eye is naturally drawn there.) Here are the exceptions: If the living room has a wall of windows with breathtaking views, this would likely be the focal point. Or, if the living room has neither a fireplace nor a view, you can create a focal point by placing a sofa against the wall with a large piece of artwork above it.
In the dining room, you might think the focal point is the dining table, but usually it's not (unless there is nothing else in the room. In this case, you should create a somewhat tall and substantial centerpiece.) Your focal point should be on the wall, closer to eye level. A good example is a large mirror or an arrangement of pictures hanging over a buffet table.
In the bedroom, the focal point is usually the bed. You can play up this area by flanking the bed with nightstands topped with lamps, and/or by placing artwork over the bed. If you do not have a headboard, be sure to add importance to the bed by hanging artwork over it and using tall pillows against the wall. Euro pillows, which are 26" square, work as a great backdrop for your smaller throw pillows.
When you give every room a clear purpose and play up the focal point, buyers will have a positive reaction to your house, and that gives it the best chance of selling quickly!