personally i like to wear a loose shirt so I don't feel all self conscious and worrying about other things while i'm supposed to be focusing on volleyball. some girls also like to wear tank tops, its your choice. only if you're allowed to wear tank tops at your school of course!
you also have a few choices for your shorts. you can wear spandex shorts, basketball style shorts(the long ones) or running shorts. if you see volleyball players they're usually wearing spandex shorts. they're nice and flexible so you can quickly sprint around and dive for the ball. my personal choice is the spandex shorts. whatever you're comfortable with! some teams they have mandatory uniforms meaning you have to wear spandex, long socks, the team shirt, and a certain type of volleyball shoes.
and for the shoes for tryouts just wear your basic gym/running shoes. shoes that support your ankles and don't feel like you could twist your ankle easily in the or anything.
aand don't forget knee pads!
shirt-just a regualr shirt with the slevees to your elbow
shorts-you should buy black spandex. dont go and wear just gym shorts cause the coaches might think your not that advanced. you can bu spandex at sports authority or dicks sporting goods
shoes-it would be good to wear some actual volleyball shoes but snce your just in middle school just wear some nice running shoes. nike and new balance are my favorite. good luck!
wear volleyball shoes you can get them at any sports retail store, spandex shorts if you have them other wise shorter shorts no basketball shorts, and a cut of t-shirt, wear your hair up in a pony tail and make sure you have knee pads and a bottle of water
all yu should waer is some shorts& tank top/muscle shirt or just wear your p.e. uniform.
dont forget your knee pads.