Before writing your own review, you might want to read a few others from professional reviewers. Since Titanic received mixed reviews, they might show you some of the weaknesses in the movie as well as its strengths. Be sure that you don't let the other reviewers' opinions alter your own significantly, however. If it's your favorite movie, begin by listing your reasons why. I am a Leonardo DiCaprio fan, so I liked the casting of the main character. I also liked the way the beginning reminiscence of Rose tied in with the end. Since much of the story is based on fact, it serves as a good biographical tale. The music was also fitting, and the costumes and set design were excellent. Hope these examples give you a good head start on your own review.