Keep yourself well hydrated. Carry plenty of fluids and juices wherever you go. Keep a small pack of glucose powder handy. Use sunglasses and caps or hats to protect yourself from sun strokes. Try to avoid extreme change of temperatures like sitting in AC at low temperatures and then suddenly shifting to a really hot outside environment. In summer you will sweat , the more you sweat , more body water you will lose. You need to keep replenishing this to avoid getting into a dehydrated state. Dehydration will aggravate heat strokes.