When you're characterizing a character in any kind of literature, you can grab almost any line of text and break it down into a meaningful analysis. If your teacher is asking you for 5 adjectives, s/he wants you to do a characterization -- identify 5 aspects of Juliet's personality. The key is, you should first read the entire scene so that you have the general context. If you don't have time to read every line, I recommend that you spend at least twenty to thirty minutes closely reading 10-15 lines of text. I am going to pull out a few lines for you and guide you in how to examine them closely.
The first time Juliet speaks is to herself, in her balcony, not knowing that Romeo stands below. She says, "O Romeo, Romeo, wherefore art thou Romeo?/Deny thy father and refuse thy name..."
(II, ii, 33-34, Romeo and Juliet, Oxford School Shakespeare)
You can identify a few aspects of Juliet's character right away by answering these questions:
How would you describe someone who speaks about the boy she just met by saying, "Romeo, why are you named Romeo? Disown your dad and refuse your name..." (One way to translate her line.) What is she asking Romeo to do? Why? Now what does that request she is making say about her personality? What does it say she might be willing to do herself?
She goes on to say, "Or if thou wilt not, be but sworn my love,/ And I'll no longer be a Capulet."
(II, ii, 35-36, Romeo and Juliet, Oxford School Shakespeare)
Translation: If you won't refuse your name, I will refuse mine (if I swear love to you).
So, what does her statement of her probable action say about her personality?
When doing close textual analysis, you always want to home in on key words. Note the use of "sworn" and "love." Remember she's just met Romeo, and now she's talking about swearing love. What do you already know about Juliet because of these words she chooses?
When you write your evidence, be sure to quote not only a phrase or a whole line, but take at least an extra sentence to home in on a word and explain its importance. You can begin such a sentence with, "Note how Juliet uses the word '___.' This word choice shows that she has ____ quality..." (The blank indicates where your adjective should go.)
Do you see what we're doing here? We've only looked at 4 lines of text, and we already have two adjectives.
I assume you have access to a summary of the scene, so you can get to another section where you will get ideas about what's happened already. Then zero in on another 2-4 lines and determine a) the basic translation using enotes and b) what Juliet's statements say about her personality.
Another section of text with excellent lines to mine for analysis is her speech that begins with "Thou knowest the mask of night..."