Those without A/C, what are your tips to stay cool during the summer?

Those soakable cloth neck-wraps work as a cheap personal cooler($5).

The Coolify2 works as an expensive personal cooler(~$200).

If you have a fridge, freeze 2 litre ice-cream containers filled with water to make large ice blocks. Then put the block in a tub to melt, and sit your feet on it to stay cool(budget-mode, $cost of tap water)