Orchestral musicians follow long lists of etiquette that includes things like: thou shall not empty your spit valve onto another's shoes. Even the act of turning pages page require conformity to norms and etiquettes. Below are some tips for orchestral string players. (While woodwind, brass, and percussion players enjoying sharing the occasional Facebook post, they don't normally have the opportunity to share music stands with other musicians.)
Who turns the page? Whoever is sitting furthest from the edge of the stage, the "inside" player, turns the page. Wait! But what does the other person do? We will get to that in a minute. The inside player is in charge of turning the page and writing down markings during rehearsals. All of this can happen while the other person is still playing so be careful not to cover up the entire music part with your hand. Also try your best not to accidentally flip the entire music part onto the floor. It has happened many times before! Check with your stand partner when you can turn the page, sometimes it will be earlier, sometimes a bit later. Below is a demonstration video from a violinist regarding turning pages.
What does the other person do? Well, when the inside person is writing down markings and turning the page, the other person should keep playing! The other person who sits closer to the edge of the stage is known as the "outside" player. The outside player is in charge of brining the music to every rehearsal and performance. Basically the outside person is in charge of carrying the music and playing the part no matter what happens. Hence why they are sitting closer to the edge of the stage so that it gives the audience the mirage that there are no interruptions.
Other Tips and Tricks: Do double check that your music part is set up in a way where most page turns occur during rests. This may incredibly difficult for violins who never seems to have rest, but try! Also double check with your stand partner to make sure your page turns suit them. People have preferences and it never hurts to ask for some feedback and suggestions.
Now time for some laughs. Victor Borge and his son, the notorious timid page turner. Enjoy!