Review the requirements of the essay, ensuring that you are familiar with the expected word count and any other stipulations. Decide on your areas for research and your approach. If, for instance, you are studying politics or developing countries, the thrust of your essay will be different from an essay on the self-determination rights of a person with cognitive disabilities. You may mention the self-determination of the individual and of a group, but you will need to focus more on one angle.
Introduce your essay by giving some examples of the philosophy of self-determination. Do not become bogged down with philosophy, however. This is a broad topic, and you need to avoid being side-tracked. In the body of your essay, discuss the main points, and narrow your discussion down to the specifics. If you are writing an essay about the rights of people with a cognitive disability, for instance, you could mention some of the injustices to this group in the past.
Give specific examples of the fight for self-determination and the thinking behind it. If you are writing about oppressed groups, for instance, you could discuss, the impact of colonialism, and the changes in attitude that led to independence for many countries. Draw your arguments together, in the concluding paragraphs, referring again to your opening points.