How do i releave my nervousness (basketball)?

ok so i have a bunch of tryout for basketball im 14 and im 6'1 and this is my first year trying for varsity and AAU (outside of school upper basketball league) but im a great player i know i am it just wheneer i get nervous all my fundementals and stuff go to hell i cant shoot any more i cant do anything someone help pleasee! i have more tryouts tomorrow