Writing an outline is an effective way to improve one’s writing ability. Usually there are two types of outlines: sentence and topic outlines. In a sentence outline each entry is a complete sentence. In a topic outline each entry is a phrase or a single word. The former takes a longer time to write and the latter is more practical and can save much time. Both outlines follow the following 4 basic steps:

1. Place a title at the very beginning.
2. Write out the main idea for the whole outline, that is, the central point of the passage.
3. Use Roman numerals I, II, III, IV, etc. to designate the main ideas in the paragraphs which are used to support the central idea of the whole passage.
4. Writing down important supporting ideas (subtopics) and expanding ideas at different levels in descending order.

The format of an outline looks something like the following:
Topic:
Thesis (central idea):
Outline:
I. Introduction
II. Main point 1
　　A. sub-idea
　　B. sub-idea
　　　　1. Supporting detail
　　　　2. Supporting detail
　　　　　　a. Fact 1
　　　　　　b. Fact 2
III. Main point 2
　　A. sub-idea
　　B. sub-idea
　　　　1. Supporting detail
　　　　2. Supporting detail
IV. Conclusion