Things You'll Need
Instructions
Consider a story that you would like to put your players through. Instead of relying on the actions of the main characters, however, your story will involve a situation and the machinations of the people around the main characters. The actions of the players will determine the end result.
Write out key scenes for your own benefit, and possibly to read to the players as they reach different scenes. (If their goal is to meet a particular prince, for example, you may want to write out the eventual meeting ahead of time and vary it as necessary as things go along.)
Create characters for each encounter that you see as likely. For example, if your players are hunting a werewolf, you will want his stats ready so that you can play out the battle properly.
Create rules for your players, and make them clear before you begin the game. For example, you may need to have a rule that states that you have the right to change rules slightly as necessary for story purposes. Players who know this up front are less likely to waste time and energy arguing with you later.
Practice telling the story for a select group of players until you are very comfortable with the rules and the role of game master. It can be unnerving to game master for a group of strangers or for many players at once.