Your walls are the largest areas in your home to have decorative impact, so their treatment is important, even if it is subtle. Combining wall covering materials is effective, and a good way of adding character to a room.
Don't be afraid of wallpaper. Try getting a big effect for little money by limiting wallpaper to a small area, selecting a strong pattern, and emphasizing it. For example, paper one end of a room and its corner pillars with panels that come in square and round corners as in the photo above.