I keep my electric bill reasonable by installing an additional window A/C unit in living room & kitchen combo. That reduces use of central A/C which uses more electricity. During the day time, I spend more time in living room & kitchen than bedrooms. Also helps to keep window blinds shut during afternoons along with additional insulated drapes.
good attic insulation is key. Another thing is to realize that late afternoon sun is actually hotter for your house than other times because the sunlight impinges directly on at least one whole side. So keeping drapes and shades down there is good as you say. Drawing in cooler air from shaded sides in the morning or late afternoon also brings down temps.
But the one thing that kills withstandability is humidity, and an AC does a good job of bringing that down. A dehumidifier also helps a lot. I use one (sometimes two) in my basement.
Watch out for those new fangled window a/c units — flammable refrigerant - R32
I use air conditioning very little as I open up windows nightly, here in Pa. Even in 90 plus it’s not until late afternoon about 4:00 or later things start to get warm in here.