I'm often asked, "What supplement(s) I should take?" Not as much by the general population, but especially my athletes.
First is getting your nutrition right to supplement your performance. Second, when it comes to improving performance, especially in sports, I recommend getting informed on and considering creatine.
I say this because I don't "prescribe" supplements to athletes. At the end of the day, especially with young athletes, it's best for you or your parents to do research before deciding what's best for you.
Creatine has been taken in all sorts of direction since it's introduction to the market. The best form of supplementation is creatine monohydrate, 3-5g per day was taken with a warm beverage like green tea. If that's not available, I've taken it with juices or other fluids that include carbohydrates.
Creatine is a great supplement for off-season training and should be cycled off every 12-16 weeks.
Some worries include muscle cramping and not being safe in the heat. Both those myths have been debunked.
Here's a short video by Dr. John Berardi on creatine myths and why it's safe to take.