Arrange a decorative throw over the back of the sofa. Drape the throw over at least one arm. Use a throw in a bright color for a plain sofa in black, white, gray or brown. Alternatively, use a patterned throw with hints of the sofa color. Use a solid throw in you favorite color from a patterned sofa to incorporate the ugly sofa into your decor without focusing on it.
Make or purchase slipcovers for the sofa. Slipcovers are typically easy to fit over the couch and can be washed or changed as often as you want a new look. The slipcover should cover the entire couch, making it look brand new at a fraction of the cost.
Pile bright and colorful throw pillows on the couch to draw attention to the colors, textures and patterns in the pillows rather than the sofa.
Incorporate the colors, textures or patterns you're placing on the sofa throughout the room. For example, hang curtains the same color as a couple of throw pillows. Accessorize the room with lamps, flower arrangements, a rug or artwork that draws from the colors in the sofa decorations.