Watch the movie as a pure spectator first to gain the normal movie experience. Watch the movie a second time, but this time as a movie critic. Take notes about your initial thoughts about the movie and include both negative and positive points.
Plan the structure of your movie response essay. Break your essay into three main sections -- introduction, main section and conclusion. Note down bullet points of what you want to include in each section of your essay.
Write your introduction. Mention the title of the movie, the name of the director and his directorial repertoire. Introduce your evaluative perspective of your movie review.
Write your middle section, which is the main evaluative portion of your essay. Discuss your view of the movie. Talk about what you perceive as being the director's vision and how well he or she executed it throughout the movie. Make a point of mentioning the challenges faced by the director. Give your opinion on the actors' performances and about the quality of casting. Pay close attention when evaluating the screenplay, the dialogue, pace, tone and the music that accompanied the movie. Compare it to other movies within the same genre to back up your point of view.
Write your conclusion. Summarize the content of your movie review to re-state the main points of your critical evaluation. Inform the readers if the movie is to be recommended.
Re-read your essay, check for spelling and grammatical errors and edit it accordingly.
Keep in mind this is merely one way to write a movie review. Every critic has his or her own style, and the more you write reviews, the more you will find your own style. This is a good template for early efforts, though.