Velour I was totally incapable of anything at all last year. Better this year but I still sweat buckets just sitting on the tram while everyone else sits there looking perfectly dry and serene 
Quick tips are use your metal/wooden blinds if you have them. Get an indoor/outdoor thermometer (on amazon) or just an indoor one (on clocks in all shops, aldi, media markt etc) and cross reference with weather apps. The MOMENT the outdoor temperature exceeds the indoor temperature, hermetically seal everything. Blinds/shutters down on the sides of the house which the sun faces. If you don't have any, cover cardboard with foil and stick it in the window to make a makeshift blind. It's important to stop it from getting hot in the first place. Then in the evening, watch the thermometer like a hawk again and as soon as the outer temperature is lower than the inner temperature, throw everything open, maximise air flow and pray for a breeze. If worried about security at night and you're not upstairs, close roller blinds but open windows. Air gets through but people can't see that your windows are open. If you live right under the roof, kick yourself, because it just acts as a total greenhouse. You can touch our eaves during the day and it feels like a radiator.
Don't use any electronics that you don't absolutely need to use. Buy energy saving lightbulbs. Don't cook anything - barbeque outside, serve cold food, reheat things in the microwave that you made on a cooler day, or make really fast cooking things like tortellini or instant noodles, maybe a stir fry, and eat out/takeaways. Absolutely under no circumstances use an oven. Rinse cooking utensils in cold water so they don't leach heat into the room. Fans cool people, not rooms, so turn them off when you're not in the room. You can drape wet towels over fans to make them colder but it doesn't help that much. Keep hydrated and wear as little clothing as you can get away with. Regular cool showers, more than once a day. Cool baths are nice too (33 is perfect!) Humidity makes heat more uncomfortable but the air might be less humid than you are used to so you could try a humidifier if you happen to have one.
To keep hydrated - don't drink too much really sweetened stuff like coke etc. Water is best of course but if you don't like water, iced tea is good and there's a reason Germans love Schorle - it's so refreshing! We like Alwa brand because it's literally just juice with fizzy water, but you can also make your own. It's nowhere near as sweet as other fizzy drinks so can take a while to get used to it. And import squash if you like it. Freeze bottles of water and drink them as they melt, it keeps you much cooler.
If your house is hot then seek out air conditioned locations. In the absence of anything else, being near water, under the shade of a tree or stone, or at higher altitudes will reduce the temperature by a good 1-2 degrees each. Stay away from tarmac as it absorbs and reflects heat back at you. If you have an outdoor pool nearby, check if it's worth buying a summerpass or multiple tickets for a reduced price, often it is, and you can spend all day there because just being near the water and a legitimate excuse to basically wear underwear in public is helpful.
If you are having sweating problems, carry tissues. Mopping it up will keep you more comfortable, and you won't look as strange as you think. Wear clothing which dries quickly and carry hair ties to tie your hair up. Think about wearing a hat. There's also a useful tip which is to use pantyliners stuck to the inside of problem areas of clothes - e.g. just under armpits or on your breastbone, the small of your back, etc. But make sure they stick and don't fall out! Pantyliners can also keep your nethers comfortable if you sweat there too.
It really helps to have regular breaks from the heat so if you have the choice of air conditioned vs non air conditioned vehicles, go for the air con even if it means waiting or paying more. If you have access to a basement, take a book, make an excuse, pretend not to notice the spiders and spend half an hour there every few hours.
Move slowly. Expect to be crabby. Don't expect to get much done other than survival on the hottest days. Try to avoid stress. Expect children to also be crabby but not really know why. Develop "air hugs" and "France kisses" (on the cheek!) instead of a normal bedtime kiss and cuddle. Own at least half as many fans as you have people. The ones which sit on the floor and blow up diagonally are good and cheap, but you'll want a normal office type fan for sleeping.
You will be better able to cope with it next year but the first year is bad!