Keep the sun out: think thick lined curtains kept closed, blinds closed, static-cling reflect or tint film (yes I have all three on the south side, it helps). If it's warmer outside that in, keep the doors/windows shut, if it's cooler open them while they're in shade.
Clothes: instinct is to strip off, but a loose garment in a moisture wicking/natural fabric can stop skin sticking together (or chafing), if it's hot but not humid, damp clothes can help, but if it's too humid, you just end up hot and damp
Sleep: again if it's not too humid a damp/wet blanket can help, I prefer to use a large bath sheet/towel as it holds the moisture better. Avoid eating or drinking alcohol for a few hours before bed. Large cooling mats (ones marketed for large dogs may be cheaper for the same product) and cool them in the fridge/freezer until bedtime, they'll keep you cooler until the gel warms through - I have two and swap them in the middle of the night. I also brought a bulk lot of reusable koolpaks - a frozen one in the pillow is great. Try to keep yourself (and your body heat) out of the room until you're ready to sleep. A fan on your bedside table feels nice, but one in an open window can help get cooler air circulating at night. If you can't get to sleep at night, try split sleeping: sleep in the afternoon/evening, then get up until the early hours, then sleep again at the coolest part of the night.
Day: frozen koolpaks - sit on them, stick one in your waistband and/or bra, use a light scarf to keep one in place by your neck, have one under your feet. If possible, try to keep your hair damp or if it's long tie it back.
Try not to add heat - turn electronics off, eat meals that don't need cooking/heating, lukewarm showers or cool baths, turn fans off if you leave the room, avoid hair straighteners, blow driers, ironing, etc if possible.
Avoid things that raise your temperature - heavy (or any) exercise, carb heavy meals/large meals, lots of sugar/alcohol/dairy/fizzy pop.
I understand the science behind hot drinks, but I prefer cold drinks in hot weather, usually water with ice, a thermos helps keep it cool - especially overnight.
Mint - original source mint (and tea-tree?) shower gel has a cooling effect, as does mint toothpaste/mouthwash. Personally I find sugar free mint gum helps too though that might be a placebo effect.
On preview just seen your update - could you both "camp" in the playroom if that's the coolest room?