There is a lot that can be covered on this topic
Walk or Cart?
Take a cooler or buy from the girl on the course?
Eat or just drink?
What kind of beverage do you prefer?
Walk if the temps are normal. Cart if its above 90*
One bottle of water if walk, Cooler with more if its hot and take a cart
Never eat on the course, just hydrate
Mostly I just drink water on the golf course, but occasionally on cool fall days, I'll take a small thermos with coffee.