The smart thermostats that you can program to change temps while you're gone help a ton unless you have a heat pump. Our solution (because I hate the power company) is we keep our AC on 81*, sounds high to most but we work outside so it feels good when we come in. We turn off AC at night and open windows, we have fans in the windows and a ceiling fan over the bed. During the day, as soon as the temp gets to 79* we shut the windows and turn on the air. You don't have to be as extreme, you can set your AC at 74 or 76 but shutting it off at night saves us a fortune.