Regular treatment:

Your bed is the most important piece of furniture in your room. Dress it with beautiful, freshly laundered linens in pleasing hues and patterns. How often you wash your sheets is a personal preference. However it’s a good idea to launder them weekly to remove dirt and dust. Use warm water rather than hot to avoid shrink fibers. If your sheets feature delicate trim, check the care label before washing.

When dealing with tough stains, use oxygenated bleach on whites and light colors. If you are concerned about spots in your bedding, better to choose white linens.

Store:

Keep spare sheets neatly folded in a cool dry closet or drawer. Surfaces should be lined with acid-free tissue paper which helps keep fabric from yellowing. Avoid storing sheets in plastic containers, which can trap moisture and foster the growth of mildew.

Replace:

Frequent washing will break down even high quality sheets. Replace them when you see obvious signs of aging such as stains, fraying hems or faded patterns.

Source: www.marthastewart.com