Here are some steps that you can take to ease the process of writing summaries.
Read the passage carefully
Determine the passage’s structure and identify the author’s purpose in writing. (This will help you to distinguish between more important and less important information.) Decide how long (approximately) your summary needs to be; this will affect how many details you can afford.
Reread
This time, divide the passage into sections or stages of thought. It often helps to label each section or stage of thought on the passage itself and/or to underline key ideas and terms.
Write one-sentence summaries
On a separate sheet of paper, write each stage of thought found in the reading. Use your own words—don’t lift whole sentences or even whole phrases from the original. It’s alright to use many of the same words as are used in the original—just don’t string them together in the way they appear in the original. Try to avoid quoting the original directly; instead, put the idea into your own words.
Write a thesis or main idea
The thesis should express the central idea of the passage, as you have determined from the preceding steps. You may find it useful to keep in mind the information contained in the lead sentence or paragraph of most newspaper stories—the who, what, where, when, and how of the matter.
For persuasive passages, summarize in a sentence the author’s conclusion. For descriptive passages, indicate the subject of the description and its key feature(s). For explanations, try to capture the gist or main point.
Note: In some cases a suitable thesis may already be in the original passage. If so, you may quote it directly in your summary.
Write the first draft of your summary
There are a couple of ways that you can write your draft such as (1) combining the thesis with your list of one-sentence summaries or (2) combining the thesis with one-sentence summaries plus significant details from the passage. In either case, eliminate repetition and less important information. Disregard minor details, but include details or examples that help to make an important point clear. Use as few words as possible to convey the main ideas.
Check your summary against the original passage
Make whatever adjustments are necessary for accuracy and completeness. Make sure you have written in complete sentences. Try to ensure that what you have written captures the flavor of the original. If the original is very rich in detail, try to include one or two of the most important details, and perhaps more depending on your length requirement. Avoid writing summaries that are so general that they become bland and meaningless. And remember, use your own words.
Revise your summary
Insert transitional words and phrases where necessary to ensure coherence. The summary should flow smoothly. Your final step should be to check for grammatical correctness, punctuation, and spelling.
Adapted from Behrens, Laurence and Leonard J. Rosen. Writing and Reading Across the Curriculum. 4th ed. 1991.