I have two portable air con units, if I owned this place I would have AC installed.
My tips.
Get up early and open the windows to let some cool air in, I often put a fan on to blow the warm air out of the window.
When it starts to warm up close the windows and the blinds / curtains unless there is a breeze, then close the blinds / curtains but leave the window open.
Sip water at room temperature or have a tea / coffee, avoid really cold drinks, they will cool your core temperature and your body will try to heat it up, making you feel warmer.
Wear a cooling towel.
I try not to put the AC on until the afternoon and I run a fan at the same time.
Cool bath or shower. Put your pyjamas in the fridge / freezer - in a plastic bag you don't want them taking on the smell of your onions.
Go to bed still wet from your bath/shower.
Are you all the same people who moan about the cold weather and the cost of heating in winter?
No, the heating was on 3 times over the winter, I used heated throws and wore a jumper.
My mum used to say I must be descended from Vikings because I don't feel the cold.
I always pay more for electricity in the summer.