Paint the walls with a light, neutral shade or a shade that's present in each piece of furniture. For example, if your sofa and chairs all have cream or light blue, choose one of those as the color for your walls.
Place a rug in the room where you plan to arrange the furniture. This will ground the arrangement and connect all the pieces. Use a pattern that complements the fabric in all four pieces of furniture, or use a solid colored rug with a simple border if the sofa and chairs have busy patterns.
Arrange the sofa and chairs around the focal point in the room, such as a television or fireplace. Place the sofa across from the focal point and arrange the three chairs in front of it. Alternatively, arrange two matching chairs in front of the sofa with the third catercorner or next to the sofa. If there isn't enough room for that, position two chairs so they flank the sofa and put the third chair across the room in a corner facing the sofa. Use end tables or ottomans to balance the three chairs.
Hang wall decor that complements the style of your furniture and color scheme. Center a large painting or grouping behind the sofa if the sofa is positioned against a wall.
Accessorize the room with decorative items that pull the room together. Add pillows to the sofa made from the same fabric as the chairs. It's OK to mix patterns if the same colors are used in each pattern.