Romeo is young and not partial to following the social customs of the day. When he sees a woman that he wants, he goes after her rather than speaking with her father first for permission to court.  He's by no means ready to get married at 14 years-old, but justifies himself in the name of love and because he loves family's enemy.  Paris, on the other hand, follows the custom of going to the father first to ask permission to date Juliet.

Romeo is also self-absorbed. When Romeo is first presented to the audience, he is in a self-pitying mood about some one he can't have. His juvenile antics continue as he kisses Juliet twice without her permission at the party; he doesn't even present himself to Juliet respectfully because he doesn't tell her his name. He doesn't even ask her what her name is and has to find out by asking the Nurse.  It is arguable that Romeo is no respector of rules or others because of his selfish acts.

Describe Romeo's character in Shakespeare's Romeo and Juliet.

Romeo's character has been interpreted in a number of ways by critics, but most would agree that he is portrayed, certainly early in the play, as particularly prone to falling in love. He is in love with Rosaline at the opening of the play, and distraught because she will not return his love. Yet within moments after meeting Juliet, he has forgotten all about his former love interest and is completely infatuated with his new love. All of Romeo's friends, especially Mercutio and Friar Lawrence, chide him for this characteristic, which strikes them as fickle. 

Related to this trait is Romeo's impulsiveness. After only a very brief encounter with Juliet, he is prepared to marry her. It is also true, of course, that she wants to marry him as well, so this characteristic is more a comment on the impulsiveness of youth rather than anything inherent about Romeo's character. Still, on multiple instances throughout the play, he takes actions without considering the consequences, such as when he kills Tybalt. 

Finally, some readers might conclude that Romeo is still rather childish and somewhat self-absorbed. For example, when he learns that he is to be banished rather than executed for killing Tybalt, he throws himself to the ground weeping, and is rebuked by the Friar for doing so. He does not recognize his good fortune. However, it could be persuasively argued that this act only demonstrates the depth of his love for Juliet.