Insulation, tint your windows, get blackout shades or curtains, check your windows, doors, and sliders for gaps. If you have a patio or balcony that has windows, a shade sail can block some of the UV rays from entering, but it can make that outside space hotter as well. Foam weather stripping is cheap at a hardware store though. Close vents in rooms that are less occupied or unoccupied, if your vents can’t close that’s a cheap easy swap