To draw a parallel, a lawyer researches and reads about many cases and uses them to support their own case. A scientist reads many case studies to support an idea about a scientific principle. In the same way, a history student writing about the Vietnam War might read newspaper articles and books and interview veterans to develop and/or confirm a viewpoint and support it with evidence.
When you outline your main ideas, putting them in a specific order is important. Place your strongest points at the beginning and end of your essay, with more mediocre points placed in the middle or near the end of your essay.
Avoid using many long, direct quotes. Although your paper is based on research, the point is for you to present your own ideas. Unless the quote you intend on using is absolutely necessary, try paraphrasing and analyzing it in your own words instead.
If you choose a topic, begin researching, and realize that it isn’t the right decision for you for some reason, don’t fret! Although it requires a bit more time, you have the ability to change your topic even after you begin researching others.