1. Read the play (if available). If not, think about the storyline, or make it up. Knowing the overall story helps you perform the monologue.
2. Learn the lines. The more comfortable you are with the lines the better.
3. What does your character want? Why are they saying these words?
4. Where are you? Are you in a church, bathroom, school hall? Specificity is really important for all actors.
5. Who are you talking to? (Important to know who you are speaking to. Is it a group of people or just one person?)