Slow down. Strenuous activities should be reduced, eliminated, or rescheduled to the coolest time of the day. Individuals at risk should stay in the coolest available place, not necessarily indoors.
Dress for summer. Lightweight, light-colored clothing reflects heat and sunlight, and helps your body maintain normal temperatures.
Put less fuel on your inner fires. Foods (like proteins) that increase metabolic heat production also increase water loss.
Drink plenty of water or other nonalcoholic fluids. Your body needs water to keep cool. Drink plenty of fluids even if you don't feel thirsty. Persons who (1) have epilepsy or heart, kidney, or liver disease, (2) are on fluid restrictive diets, or (3) have a problem with fluid retention should consult a physician before increasing their consumption of fluids.
Do not drink alcoholic beverages.
Do not take salt tablets unless specified by a physician. Persons on salt restrictive diets should consult a physician before increasing their salt intake.
Work Less, Rest More.
Know what to do for heat cramps, heat exhaustion, and heat stroke.
Spend more time in air-conditioned places. Air conditioning in homes and other buildings markedly reduces danger from the heat. If you cannot afford an air conditioner, spending some time each day (during hot weather) in an air conditioned environment affords some protection.
Work in well ventilated areas. All workplaces should have good general ventilation as well as spot cooling in work areas of high heat production. Good air flow increases evaporation of sweat which cools the skin.
Don't get too much sun. Sunburn makes the job of heat dissipation that much more difficult.