Block sunlight coming in windows. Ideally with exterior blinds or reflective material on the glass. Interior blinds block light but not heat.

AC circulation. If your AC isn't hooked to your forced air than you'll want to circulate the air in your house to bring down the average.

Vent thorugh windows at night. Wait until it's below 20C and open at least 2 windows. Use a fan to force more airflow.

Hang out in the basement.

Upgrade your roof/windows. If you're from a warm climate your house probably isn't well insulated to keep heat in during winter; which also means that it doesn't keep heat out. Newer windows block UV light and have a higher R value which prevents heat from the air against the glass.

Plant climbing/creeping plants. They will absorb sunlight that would hit your house/etc and can create a micro climate several degrees cooler than the ambient temp.

Avoid wearing cotton and dark colours.

Wear a 360 large brim hat and sunscreen. Some of the "hot" sensation is actually UV damage.