Make sure you eat plenty .You don't want to compound the heat problems with lack of energy.Also you tend to overheat in the head so it is important to keep this area well ventilated,cooland shielded from the sun.In addition to a well ventilated helmet a tactic I use is to cut my hair as short as possible then drap a water soaked bandana over my head so it hangs down on sides and back blocking the sun from your neck(like the desert headware you see in the far east)Then hold it in place with a water soaked sun visor to shield your face on top of which you can put your helmet.I guarantee you this cools you right down .