Select a book that is uplifting or beneficial to you. For example, the book "The Secret" is about the benefits of having a positive attitude towards life. Reading and then writing about this book could be beneficial to improving your outlook on life.
Read the book thoroughly, keeping a notebook nearby to write down thoughts and ideas as well as quotes that stand out to you. Make note of the pages these ideas are drawn from, which will make it easier for you when you are composing your essay.
Brainstorm about the focus of your essay as well as the layout of it. Decide if you want to focus on the message of the book as a whole or one aspect that stood out to you. For example, in "The Secret," there are different sections that relate to different aspects of your life, such as finances, love life and health. Choose one section that particularly intrigued you to flush out in the essay.
Compose drafts of the introduction, body and conclusion of the essay. The introduction can introduce the book and its impact on you. The supporting paragraphs can refer to different sections of the book or the different impacts the book had on you. The conclusion will tie all your points together and relay how you intend to utilize the reading and reflecting on the book to better your own life.
Clean up the essay, correcting any grammar mistakes and fine tuning the flow of the paragraphs and the transitions. Pay special attention to the introduction and the conclusion, making sure the former captures the reader's interest and the latter thoroughly explains the book's impact on you.