I think it was me that answered your original question about the differences between these two scenes, so I will carry on and give you some ideas on how to start your essay. Key to making your essay standing out is coming up with some kind of "attention grabber" that will draw your reader in and make them want to read more. I always say to my students that they need to imagine me sitting up late at night marking a pile of their essays. Do they want to bore me or do they want me to sit up and take notice of their essays? Obviously, anything you can do to make your introduction interesting and eye-catching will help you get a better mark.
Therefore if I were you I would think about some of the kind of themes that these two scenes bring up. The foolishness of Benedick and Beatrice in vowing not to love the other and then suddenly changing their mind is a good one. You might want to start your essay with a sentence that captures this irony and relates it to today, such as: "Love has always had the ability to make us act in foolish ways and to make us attracted to those whom formerly we have despised." This sets the context and then leaves you free to present your thesis statement and a very brief outline of the main points you will discuss in your main body.