If you don't have an air conditioner, or even if you do but are looking to cut back on your electricity bills, consider a good old fashioned fan for keeping yourself cool in the summer heat. They don't cost much to buy or use, and are a more eco-friendly alternative to boot. Here's how to make sure you're using yours right.
Though it may seem counterintuitive, it's actually best to position your fan in a window, facing out. This helps air flow through the room-which keeps it cool in the process. Since hot air rises, you want to put the fan as high as possible (preferably in the top of the window). Close the window around the fan (it helps to invest in a rectangular window-specific fan for this reason) to avoid reverse air circulation (which is what happens when the air sucked through the fan goes back around the fan and is sucked back in). You can use paper or cardboard, or even drapes or slats of wood to cover any gaps between the windowsill and the device.
To maximize air flow, if you've got two windows that face each other in a room, place one fan facing out (pick the side of the room that's warmer or sunnier, and position the fan as high up as possible), and the other fan facing inward (on the cooler or shadier side, and placed as low as you can). You can also place the low fan on the ground in a doorway for a similar effect.
You'll keep your home coolest if you run the fans during the coolest part of the day, as well as at night, and close the blinds during the sun's peak hours.