The topic of your paper is important. Try to sum up the point of your paper in one sentence or phrase. This will help your paper stay focused on the main point.
What main points will you cover? The introduction usually introduces all of your main points, then the rest of paper can be spent developing those points.
What is the first point you want to cover? If the paper centers around a complicated term, a definition is often a good place to start. For a paper about a particular theory, giving the general background on the theory can be a good place to begin.
After you have the main point, create points under it that provide support for the main point. The number of categories that you use depends on the amount of information that you are going to cover; there is no right or wrong number to use.
By convention, each category consists of a minimum of two entries. If your first category is Roman numeral I, your outline must also have a category labeled roman numeral II; if you have a capital letter A under category I, you must also have a capital letter B. Whether you then go on to have capital letters C, D, E, etc., is up to you, depending on the amount of material you are going to cover. You are required to have only two of each numbered or lettered category.