The life span of a T-shirt is probably not as long as you think it is―or wish it were. Once a tee goes through one, maybe two, summers, it's ready for under-sweater-only status. But a few simple tricks will help keep it as white and shapely as possible.

• Most T-shirt manufacturers recommend washing in cold water, yet according to Jane Rising, a manager at the International Fabricare Institute, detergents function better at higher water temperatures. So if you dare challenge the label: Wash in warm water; hot water can cause shrinkage. Use the permanent-press cycle for drying.
• Use fabric softener to avoid wrinkles, and remove clothes as soon as the dryer shuts off.
• To keep whites whiter, don't overload the washing machine. Put in only whites―no prints or pastels.
• To help restore original whiteness, try a bluing agent, like Mrs. Stewart's Bluing, which counteracts yellowing ($12 for three bottles at mrsstewart.com).