If you want to excel in squash, you definitely need to know a lot about the game and how to play. You need to spend a lot of time on court so you can improve your shots, your tactics, your movement, and other aspects of your game.
Perhaps as important, you need to spend some off-court time to learn about how junior squash works in the US. For that, there's a great Guide to Junior Squash provided by US Squash.
It tells you all about ratings and rankings, tournaments and which ones matter most, the US junior development program, and requirements for conduct and rules.
Spend a bit of time studying this guide off-court, and it will pay off handsomely.
