Cotton sheets represent both the peak of luxury in bedding--when boasting a high thread count--or the epitome of affordability. No matter what purpose you're using them for, cotton sheets are prone to wrinkling if you leave them tossed about, or even if you just neglect them a bit too long during the laundering process. The best way to keep wrinkles out of your cotton sheets is to keep them from getting wrinkled in the first place. If you don't manage that the first time around, you have several options for getting the wrinkles out.
Remove your cotton sheets from the dryer as soon as they're dry. The exact drying time needed will vary depending on what sort of cotton is in the sheets, how many sheets are in the dryer and how each individual clothes dryer works.
The sheets being dry won't necessarily coincide with when the dryer turns off, especially if you're running it on a timed cycle. You may need to open the dryer door and check to see if the sheets are dry several times toward the end of the drying cycle.
Fold your sheets and put them away immediately upon removing them from the dryer; this is the only way to ensure that they don't set wrinkles in as they sit, either in the dryer or in the laundry basket, waiting to be folded. If the sheets are still just out of the dryer, you can smooth most wrinkles out of the sheets with your hand as you fold them.
Return any sheets that still show stubborn wrinkles to the dryer, along with one or two clean, water-saturated washcloths. The water from the washcloths, combined with the heat from the dryer, will steam the wrinkles out. Check on the sheets every three to five minutes and remove them the instant they're dry. Once you've done this a few times and have a feel for how long the process takes in your dryer, with your sheets, you won't have to check on them as frequently.
Fold the steamed sheets right away, as directed above.