Point #1: Keep it neutral. Neutral colors and patterns will stay in style longer than trendy prints. You'll be less likely to tire of something that doesn't catch your eye the moment you walk into a room. Neutrals also take the backseat and let your accessories shine. If you do want bold pattern in your upholstered pieces, keep it on the smaller ones.
Point #2: Line up the pattern. Patterned fabric should line up throughout the piece. This is especially important on large pieces such as sofas, where the pattern should be unbroken from top to floor and from side to side. Even though the furniture is made of separate pieces, from a distance it should look as though one piece of fabric drapes the entire piece.
Point #3: Get a swatch. Stores that sell quality upholstered pieces normally allow swatches to be checked out. Whenever possible, keep the swatch for several days so you can live with it and see how it looks in different kinds of light. Some stores may ask for a deposit on the swatch, but they should refund it when you return the fabric. Other stores may allow you to order a memo sample -- a larger swatch that also must be returned.
Point #4: Picture it. Reputable stores show you how a custom-ordered piece will look. If you are shopping at a store where you pick the frame and fabric separately and have the piece custom-made, ask to see a computer image of what the finished piece will look like. The stripe or floral that looks demure on a little swatch may be overpowering on a five-foot-long sofa. If the store cannot show you a picture or computer image, go elsewhere.