1. You don't need to cool "a house" - just the room you're in. If I do run the air conditioning for 20 minutes before bed, I'll block under my door to keep that cold air in.
2. If there's no reason for you to be in a hot house, then don't be. If I'm teleworking, I end up not just being cooler, but also happier, if I find a nice quiet spot somewhere else. I'm lucky enough that I have a free museum not far from me that has an indoor courtyard I can work at.
3. Air circulation and window fans that expel heat from the room can do a lot. Fan quality and fan placement is tremendously important for circulation.
4. At least the last two minutes of your shower should be cold.
5. Blinds should be closed during the day.
6. Drink lots of water, of course.
I think there's more I can probably do. For example, I've been meaning to research reflective blinds to see if they do more than normal blinds at keeping out heat. (Shutters aren't an option for my building.) Dehumidifiers are also something I want to look into.
I haven't personally found that bed sheets make much of a difference, outside the way too obvious things like I don't use my winter (flannel) sheets. But this might reflect that I only buy nice ones.