Call the theater for an audition. Make sure to choose a time that will allow you to arrive early.
Be sure that you under stand the audition requirements. They are not open to interpretation. If the director says prepare two three-minute Shakespearean monologues, don't prepare one 10 minute monologue from a Neil Simon play. Ask if the director wants a piece from the play that is being produced, or another Shakespearean play.
Begin a search for a monologue. Bookstores are full of Shakespearean monologues. If you are coveting a specific part, you might want to choose one of that character's monologues.
Read the entire play! It's the only way to get insight into your character's motives.
Study the Shakespearean language. There are a number of Shakespearean glossaries on line.
Purchase a DVD of a Shakespearean Play. Note the rhythm of phrasing of the speech. However, resist the temptation to imitate the actor. Find your own interpretation.
Dress appropriately. While coming in costume is tacky, clothing that alludes to Renaissance period will help you get into character.