I keep packages of Emern-C with me for electrolyte and vitamin boost. You just pour a packet into your water bottle and shake it up. I won't say it tastes great, but it doesn't taste bad. It boosts your energy because of the B vitamins, so I'll use it as a pick-me-up if I'm feeling under the whether or dragging ass (emergen-c and alka-seltzer plus cold medicine are my hangover cures). Here's a link but you can by boxes at grocery and drugstores:
http://shop.emergenc.com/Original-Formula/c/EmergenC@OriginalWe also keep potassium pills (be careful, it's easy to overdose), bioplasma cell salt tablets in our kits. Emergen-C and bioplasma cell salts both have potassium, so pick one of the three supplements, don't overlap. As long as you drink water with them, these are all useful supplements for preventing or recovering from heat exhaustion/dehydration.
To make a natural swamp cooler in the heat, we wet our shemaghs and drape them over our heads and shoulders but, that may only work in dry heat, not humid climates. Wetting your hat works as well, at least in semi-arid and arid climates.
Head, armpits and groin are all important areas for controlling thermoregulation (regulating heat). If you can cool any of those areas down significantly, you can bring your core temperature down (that's why those shirts with armpit vents are so nice in the heat). If possible, place icepacks or cold water bottles under arms and between thighs if you are suffering from heat stroke or exhaustion. Reversing that thinking, to stay warm you wear a hat to prevent heat loss and wear long underwear that wicks up moisture and dries fast (like polyester) to prevent heat loss from sweating in underarms and groin.
I will try the homemade electrolyte recipe next time I have all the ingredients (no oranges at the moment), good stuff guys!