What should tennis players pack in their tennis bags?
Rackets: This is self-explanatory. I like to have two to four sticks in my bag at a time.
Overgrips: If you play in hot and humid conditions, you will certainly have to change your overgrips very often. The hottest condition I have played in is Florida. I was in the south of Tampa Bay, and playing there for an hour made me sweat even more than playing in California for multiple hours. It is important to know what overgrips to use. Some brands like Tourna have multiple types of overgrips depending on the humiditiy, so know the conditions ahead of time, and plan what overgrips to use.
Dampeners: If you use dampeners, carry an extra or two. It is possible to lose your dampener, so it helps to have one in your bag.
Hats: I cannot play without a hat. I may carry an extra in case I sweat too much.Balls: If you are practicing at an academy, they will likely provide the balls, but if you are hitting with someone, have some spare balls or cans of balls in your bag so you can always use fresh balls, or add if you lose some.
Towels: In case you sweat.Clothes: Same as towels. You never know how much you sweat.
Shoes: This is a hot take, but I do not bring my tennis shoes in a bag. I wear them to the court. If you prefer to change from your regular sneakers to your tennis shoes, or to switch to sliders afterwards, have a shoebag ready to go.
Water bottle: Hydration matters!
Electrolyte: I like to have those electrolyte powders so that I can add it quickly to my water bottle and stay hydrated. My favorite flavor has to be lemon.
Snacks: I do not usually like to eat snacks on the court, but if I know I will be on the court for a long time, I might take a bite of a granola bar.
Sunglasses: Hat and sunglasses come in handy for playing outdoors.Sunscreen: Outdoor sports necessity.Lucky Charm (Optional): Some people like to put key chains, and others like to put their diaries. I have some lucky charms given to me by a player I was working with for a while. They are all in a pouch along with overgrips :)