Stuck behind a slow group and want to get some extra practice? Damaged, out-of-service balls are perfect for this purpose. (Or if you're having a bad day and are sick of throwing new balls in the water and woods.)
This includes jacket, pants, hat and rain gloves. Make sure you have a cover/hood for your bag so your sticks stay dry, too.
Not only to label your ball, but can be a de facto pencil for the scorecard.
As in, multiple. One for your club, one for your hands, neck and face, and one in case things get wet.
Solid chance you'll forget to snag a card in the clubhouse or your cart will be without one. Also good to have a spare.
I'm told these are vital to the teeing-off process.
Maybe you're playing 36 and want to change between rounds, or you step in a puddle or lake and don't want soggy feet the rest of the day. Just make sure to take out the used pair after the round, or else risk a smell stewing in your bag that's worse than death.