Water and Gatorade is a good choice. Check with the coach on what and how much to drink before competing. No, this was not a typo. This is one of the hard facts of basketball. It is true.
Continued practice is essential for precision and successful shots.
It is a good idea to shoot a few hoops every single day. Try doing this in your spare time after school, at lunchtime, or anytime that you get a chance. I've heard that certain foods can give you energy. Although athletes should always maintain a healthy diet low in fat and high in carbohydrates, this is especially important the few days prior to a game. Most runners try to eat loads of carbohydrates a day or so prior to the competition.