Dark circles are usually a sign of dehydration in the body. Make sure that you drink at least two litres water daily. Restrict the intake of salt as it contains fluid retention properties causing dehydration.
Eat well balanced diet. Have fresh fruits and vegetables to provide the body with essential vitamins, minerals and anti-oxidants that aid in having good skin. Cut down intake of very oil or spicy food.
A paste of crushed mint leaves along with grated cucumber applied on dark circles will help reduce the fatigued look.
A paste of almonds soaked overnight mixed with a few drops of lime juice will reduce darkness under the eyes.