Lighter colors reflect the sun's heat. A radiant barrier has a metallic surface which reflects radiant heat. Natural ventilation can be used to take away the heat that penetrates into the attic space. This is done by venting air to the outside. The basic principals of home ventilation are the same for attic ventilation.
Hot air rises, so assist it in rising.
Bring air in as low as possible and vent it out as high as possible. Since hot air rises, the interior ridge of the attic will have the highest temperature. This uppermost part of the attic is the most beneficial area from which to exhaust the hot air. This can be done with ridge vents, gable vents or turbine ventilators. Ridge vents will allow heat to escape all the time while turbines and gable vents work best with a breeze.