Choose light color vehicle: That still helps Choose vehicle with smaller window or windows have more verticle angle. I hope I am not going too far. Tint windows: watch local law, some area you may not do that on all windows. Maintain AC.
Keep enough fluids:
Wash water Engine coolant Brake fluid Engine oil: It's good idea to change oil more often if weather is really hot. Check oil quality by its color.
Parking
Park under shade, use covered parking if possible. Park under tree is a good idea but you may need to wash your car more often since trees and small animal leave harmful chamical to car's skin Vent cabin: Its a good idea to vent when weather is hot Use dashboard cover: believe it or, dashbaord cover really cools. Link Use sunshade: Like I can't state that enough. use our xshade and cool better.
Check tire pressure: do that when there is an weather change. Like from cold to hot, hot to cold. Always maintain proper pressure Check brake pad: Brake tends to fade more quickly when it's hot.
Drive less: reduce exhaust gas and help prventing global warmming. We are using too much gas/oil already. Link