No copies of Shakespeare's plays written in his own hand have been discovered, but most Shakespeare scholars agree that William Shakespeare likely wrote very few, if any, stage directions for his plays.
Scholars also agree that Shakespeare had little or nothing to do with the publication of his plays during his lifetime. Early printings of Shakespeare's plays were "pirated" versions—stolen copies of the plays or prompt scripts used in performance and published by book printers hoping to make a "quick buck" on a popular play.
The modern published versions of Shakespeare's plays are scholars' and editors' "best guesses" as to what Shakespeare actually wrote based on the different versions of his plays that have come down to us over the years. The stage directions in modern versions of Romeo and Juliet are written by editors, not by Shakespeare.
For example, modern editions of Romeo and Juliet begin act 1, scene 1 with "Verona. A public place. Enter Sampson and Gregory with swords and bucklers of the house of Capulet."
The first published version of Romeo and Juliet in 1597 (the "First Quarto") begins with, "Enter 2. Seruing-men of the Capolets." There's no mention of Verona or "swords and bucklers."
It's possible that even this brief stage direction in the 1597 version wasn't written by Shakespeare, for the simple reason that it's not necessary. It's obvious that the first scene involves two characters, and it becomes clear as the scene progresses that the play is set in Verona, and that the two characters in the scene belong to the house of Capulet.
Modern versions of the beginning of act 2, scene 1 include the following:
A lane by the wall of Capulet's orchard.
Enter Romeo alone . . . .
Climbs the wall and leaps down within it.
The "First Quarto" mentions nothing about Romeo climbing over a wall. Even the "First Folio," published in 1623 by Shakespeare's friends and fellow actors, and which is used as the reference for most modern versions of the play, makes no mention of Romeo climbing over a wall.
There's also no mention in the "First Folio" of Juliet appearing at a window or on a balcony, or of Romeo climbing up to the balcony. These stage directions were added long after Shakespeare's death.
Published versions of Shakespeare's plays are meant to be read, and scholars and editors add stage directions to the play—as well as act and scene breaks, which don't appear in the older versions of the plays—to make the plays more understandable for readers and to give staging suggestions to actors and directors.
The stage directions in published versions of Shakespeare's plays can help clarify the staging of a play and help readers visualize the action of the play, but the essential elements of character, conflict, and theme in Romeo and Juliet appear wholly in the lines of the play, not in the stage directions.
One interesting stage direction that contributes to conflict and theme can be found in the opening scene. Capulet's servants, Sampson and Gregory, are described as entering the stage "armed with swords and bucklers," meaning swords and shields. The irony in this description is that these two men are just servants walking through town on some errand, plus this play is set during a time of peace in Verona. So what are these servants doing walking through town with swords and shields? The description shows us just how much importance Lords Capulet and Montague are placing on their feud. They take the feud so seriously that even their servants must walk through town carrying weapons in order to either defend themselves against or start a fight against anyone they may encounter, which points to both a central theme and conflict of the story. A central theme deals with the anguish and turmoil that blood thirsty fighting brings, while a central conflict deals with man vs. man and man vs. society.
Another interesting stage direction can be found in Act 3, Scene 1. After Tybalt "stabs Mercutio" while being held back "under Romeo's arm," Tybalt then "flies with his followers" (89). It does not quite seem characteristic of Tybalt to run away from a fight, especially after just having caused damage. It seems unlikely that Tybalt ran from fear of the Prince's consequences, considering that Tybalt was the one who challenged both Romeo and Mercutio to a dual in the first place. Hence we can assume that Tybalt fled because, just like a typical bully, he truly is a coward. Tybalt's bullying, cowardly behavior also relates to the central theme of the damage man's hatred can cause. Tybalt's bullying nature and fiery temper were fed by the existence of the feud. Had the feud not existed, his poor character and nature would have had fewer outlets to show itself, thus, sparing his own life as well as others'. Tybalt's nature also relates to the conflict of man vs. man and man vs. self. Tybalt challenged Romeo, but at the precise moment when Tybalt fled the scene, Romeo had the choice of fleeing from the fight as well. Had Romeo made the decision to flee, Tybalt would have been punished by the Prince and Romeo never would have been banished, which would have spared his own life as well as Juliet's.