One of the most common causes of dry eyes is a lack of oil film on top of the tears. If the oil glands become plugged up there is less tear film and faster evaporation of the tears. Warm compresses can soften up the oil in the glands and allow it to spread over the tears more completely. Ideally this should be done twice a day.
Several companies make moist heat masks that make the treatment much easier than it used to be with warm washcloths. The Bruder mask is one of the best.