What are some of Juliet Capulet's character traits?

One of Juliet's most obvious character traits is courage. For a girl of only 13 she displays a rare ability to be brave in the face of overwhelming obstacles. Despite the fact she knows her family will object, she is courageous enough to pursue what she truly wants. She falls madly in love with Romeo and will not be dissuaded from this love by the reality of the feud. Her real courage, however, comes later and she displays it in three different scenes.

In Act III, Scene 5 Juliet has the courage to stand up to her father and refuse the marriage pact with Count Paris. She overcomes her father's angry onslaught and displays fearlessness in the face of a difficult dilemma. She shows tenacious loyalty toward Romeo even after the Nurse advises her to forget him and marry the Count.

In Act IV, Scene 1 she is determined to do whatever it takes to stay loyal to Romeo, even if it involves some frightening or dangerous task. She tells Friar Lawrence,

O, bid me leap, rather than marry Paris,
From off the battlements of any tower,
Or walk in thievish ways, or bid me lurk
Where serpents are. Chain me with roaring bears,
Or hide me nightly in a charnel house,
O’ercovered quite with dead men’s rattling bones,
With reeky shanks and yellow chapless skulls.

The Friar's "remedy" is for Juliet to fake her own death and the girl agrees. She shows tremendous courage to embark on such a drastic course of action. Her fears almost get the most of her in Act IV, Scene 2, but she eventually summons the will to drink the Friar's potion.

In the final scene, she again demonstrates her dauntless personality in the face of catastrophe. When she awakens to find Romeo dead of poison, she could have just gone with the Friar, but she didn't want to live without her love so she stabs herself with a dagger. Some may say she was the victim of fate or impatience or simply naive youth, but the audience has to admire Juliet's courage. 

Other possible character traits that may be identified with Juliet could include spirited, willful, dynamic (in that she changes over the course of the play from an immature girl to a mature woman who follows her heart), genuine, heroic, idealistic, passionate and adventurous.