Choose a novel with a character in it you want to sketch. Read the novel thoroughly and make notes about the character's physical description, habits, and any quirks. Decide if those quirks impact the outcome of the story in any way, positive or negative. Decide what your character's goal is in the story and what motivates her to achieve that goal. Ask questions of yourself about the character you are sketching. Is this someone you would like to know or hang out with?
Make notes on what the character says throughout the story. Especially indicate if there are repeated words or phrases she uses and if she speaks with any identifiable dialect. How does this affect your character's role in the story, especially concerning the way other characters view her?
Write six to eight paragraphs about your character. Start by summarizing who the character is in general, then detail your character's role in the story and her goals. Tell readers why the character is important to the story. Is she a protagonist (good guy) or antagonist (bad guy)? Does your character play a major or supporting role?
Summarize the outcome of the story as it relates to your character. Did she achieve her goal in a satisfactory manner? Do not inject opinions into your sketch. All of the information you include should be based on the character in your story and what the author tells you about her. Keep the focus of the character sketch on the story as it relates to the character you are sketching.
Format your character sketch according to the guidelines put forth by your instructor. This might be MLA format or APA style (see Resources). Some instructors don't require a specific format, in which case you should format your sketch as a standard manuscript.