Walk around the room and determine where your eye naturally goes first. For example, if the room has a fireplace, that becomes a natural accent wall that you can enhance with paint. However, accent walls shouldn't have doors or windows; they should just be uninterrupted stretches of blank space.
Locate the area of the room that contains or will contain the most important piece of furniture. For example, in the living room this is the couch, and in the bedroom it's the bed. The wall behind this piece of furniture often makes a good focal point for the room.
Look around and assess the shape of the room. If the shape is odd, such as a long and narrow room, accenting a far wall with a dark color helps the wall appear closer and makes the room feel less oblong. On the other hand, if you have a standard rectangular- or square-shaped room, choosing a wall in a dark or dull corner can help liven up that area.
Walk around the room and decide what the room's best feature is, then choose a wall that can best accentuate that feature. For example, if you have a fine piece of art on one wall, painting that wall a color drawn from the piece of art helps to accent it.