Shade the west side of your house by planting deciduous trees (they loose their leaves in the winter).
If water is abundantly available, water early in the morning. Water deep.
Use insulated shades or curtains at the east, west and south windows. In a pinch, hang a quilt over the windows.
Hang outdoor curtains on the West side of your porches.
Install awnings on the outside of your west windows.
Install an whole house attic fan.
Use cotton slipcovers or sheets over upholstered furniture (couches, recliners, big pieces). It feels cooler.
Don't turn on incandescent lights - they heat. Another reason to use the new energy saver bulbs.
Drink lots of water. Iced water will fool the body into thinking you;re cold and may heat you up more.
Although no contractor in his right mind will do it now, plan to insulate the side walls and attic.
The same principals apply to heat loss as it does to cooling loss. A drafty winter house is a house hard to cool in the summer.
If you need a blanket, sweater, or have goose bumps in the house, turn the AC thermostat up. It is simply wasting money.
Don't drink caffeinated drinks - they dehydrate you.
Consider installing a ceiling fan on your porch.
Do anything that produces heat (oven, dryer, boiling) very late at night or very early in the morning.
Hang clothes outside to dry.
Use a crock pot or roaster instead of the oven and cook top.
Turn the water heater down a few degrees. If you must turn your cold water on high to make the water comfortable, then your water heater is turned to high.
Provide pets plenty of water and shade.
If you don't have AC: Close all shades and curtains from first light to dusk. In the afternoon, open one window on the West or South and put a box fan blowing out (upstairs if you have more than one floor). Open one window on the North or East and put a box fan blowing in (downstairs). Keep all other windows closed. This will draw the cooler air into the house and exhaust out the hot side.
Drink plenty of water (not tea, coffee, pop, alcohol or sugar drinks). Any drink that makes you urinate more is actually working against your cooling system.
Eat light foods. Heavy or fatty foods take energy to digest and that means it will heat your body.
Wear natural fiber clothing. It absorbs and wicks the sweat off your body.
Wear a light colored hat if in the sun. Wear plenty of sunblock and reapply. If possible, do any outside chores early in the day.
Don't wear cream or lotion. It will make you hotter because it keeps the skin from breathing and sweating properly.
The more you open the freezer and refrigerator, the more it must run to cool down. The engine will run more and that throws off heat. If you have a big family that wants ice all day long, consider putting ice in a cooler each day.
Some of these tips I acquired when I was the Consumer Advisor for a utility. Others are from old house plans constructed prior to AC. Some are common sense tactics.
Remember: Winter is only a few months away!