I'll echo what most others here have said. I walk 27-36 holes every Saturday and Sunday in SW Georgia. I normally go out around noon so it's can be very hot, below are my recommendations.
-Push cart. I use the Clicgear 3.5+
-Keep hydrated and drink plenty (I don't put anything in my water, as I approach the refill on hot days I'll dump the remaining water over my head or down my back before refilling.)
-Lightweight, wicking clothing
-I keep two towels, one I keep...