The essay should progress towards the conclusion. At this stage, all you are preparing is the outline, which will take you from one end of the essay to the other, like a road map. It should be constructed to keep you from losing your sense of direction as you research and write the essay. A good outline will ensure that everything you write in the essay supports your thesis, preventing you from wandering off into the tempting byways of irrelevance.
Construct your outline by listing all the important points you want to cover in your essay. You should provide one main point for each paragraph. Start with the introduction, under which you will write out your thesis statement and work through logically, point by point, until you reach the conclusion. Categorize your points according to their importance, keeping in mind the method of organization you intend to use.
Group related ideas together under general headings and arrange them so they flow logically. It may be useful to number each point, giving more weight to major points and less to minor ones (e.g. A 1 2 3 B 1 2 3); alternatively, you can simply set the points off further from the margin of the paper as they decrease in importance:
Some essays read as if each point had been written on an index card, then the pile thrown down a flight of stairs to determine the order. Make clear why one point follows another: each point in your outline should connect with the next; each main category should be linked to your thesis; and each sub-category should be linked to the main category. Focus your outline by discarding anything not useful or pertinent to your thesis.
One of the most helpful things about a full outline is that it will quickly make clear to you where the gaps lie. If you don't yet have enough support in one area, you will know that you have more reading or thinking to do. Remember that sometimes your reading will unearth new facts or idea--and you will modify your essay to reflect them.