Have put some ideas on another post but some ideas for here. If it is not very hot now and you are able to , cook some dishes and freeze them in appropriate portions so that when it is hot, you can just get something out and only have to reheat in the cooler evenings. Get plenty of bottled water, fruit juice etc so that you can put some in the fridge when the weather is hot. Avoid alcohol when it is hot, it doesnt help at all.
Keep the curtains closed and also the windows, until the temperature outside is cooler than inside. Doesnt sound right if you can hear a breeze outside but if it is hotter than the inside temperature, wont help to open them. Where you have a wide windowledge put a bowl of cold water on it. If you have an old hot water bottle, fill with very cold water and a little ice, wrap a thin towel round it and then you can sit with your bare feet on it. Very cooling, or if you dont have that , get one of those lunch box freezer blocks and do the same.
Rinse a clean flannel in very cold water, and squeeze it out so no running water from it. If you have to go out, take with you a bottle of cold water from the fridge and put the flannel (in a plastic bag) next to the water. That helps to keep the flannel cool and also you have some cold water if you need it. When you feel very hot, use the flannel on your face , hands and wrists. At home , sit away from the windows in cooler areas and you can use the same flannel ideas , but also I leave cold water in the washbasin, and you can cool yourself in the same way. I also wet my hair and very lightly take off the running water and then allow my hair to dry naturally. I do think keeping hands and feet cold helps in general, as of course you can then also run your cold hands on your arms or legs to help cool down.
If you are able to go out for shopping, then going as early as possible and if walking choose the shady sides of the street. It is worth sticking to the shade and only going across to the sunny side where necessary. If you have to be out at a hotter time of day then take an umbrella as a sunshade. Obviously wearing loose clothing ,cotton or silk if you have it but not manmade , which tends to stick to you. At home ,I recommend ditching the bra ladies, so nothing tight. That cold flannel can sit round your neck if it gets too hot, and at night the ever useful cold water bottle can be treated like the winter warming pan, by running it over your pillow and sheet to cool it down for you. If you have a spare pillow, keep by your bed, then if you wake hot and sweaty at 2 am swopping the pillow for a cooler and drier one can help you get back to sleep.
Hope something might be of use here