Determine your accent colors. If the focal point is a piece of artwork, add throw pillows that coordinate with the colors in the piece. For example, if the couch is tan and you have an attractive painting with bold yellow flowers with red centers, use these colors for your throw pillows.
Balance the number of pillows down the entire length of the sectional. Piling two or three in one corner of the couch leaves the rest of the sectional looking bare.
Vary the shapes of your pillows to create an interesting array on your sectional. Buy pillows that coordinate well with each other in a mixture of geometric shapes.
Purchase pillows with different textures, such as ruffles, fringe or different types of weaves, if you are using throw pillows in just one color. This adds visual interest and prevents the sectional from looking boring.
Use solid-colored pillows as a background. Throw pillows tend to be expensive. If a certain pillow is exactly what you desire for the sectional but it would be too expensive to buy as many as you need, choose solid-colored pillows to place beside and behind the more expensive styles. This allows you to provide enough pillows for comfort and have the design you prefer.
Choose pillows with the same colors but in different designs. For instance, if you have a plaid pillow that is primarily blue with tiny ivory stripes, select an ivory pillow with a blue flower in the center to place next to it.