Describe the ethical issue you intend to solve. In your description, go beyond the obvious, and try to embed your description in the larger moral and ethical literature.
Give a charitable (fair-minded) reconstruction of the argument that you will be opposing. In a short essay like this, it is best to confine your analysis to a small argument, from within the larger problem. In such a short essay, it would be difficult, for example, to adequately defend the thesis, “I shall argue that abortion is immoral.” Instead, focus on some smaller thesis such as, “I shall argue that Reiman’s argument for what makes killing wrong is incomplete.” In a case like this, the charitable reconstruction would be of Reiman’s argument for what makes killing wrong.
Introduce any empirical evidence that you’ve collected, and explain why it is relevant to your topic and how it helps to support your thesis.
Evaluate the argument you will be opposing in terms of the logic and principled support that the author is able to give to it. First, an argumentative essay is much easier to structure if you have some specific argument you can discuss critically. Second, since this is an argumentative essay, this evaluation is the most important part of the essay, will constitute your principal objection, and will be the place that you can introduce your own position and contribution to the debate. Take some time to develop it carefully.