the author's full name and title of the work being summarized, typically in the first sentence,
the author's thesis (also known as the author's claim or sometimes main idea),
all other key ideas from the text (or main ideas)
ideas arranged in the same order and with the same emphasis as the original text,
(sometimes) a few pieces of key evidence - most evidence is not discussed in a summary,
a few significant direct quotations, and
author tags indicating that the ideas discussed are the author's and not the writer's.
The trick to summarizing effectively is to paraphrase all of the author's main ideas accurately while avoiding too much detail or too many direct quotations. Some strategies to help you do this are:
Before you start a summary, look up key words or phrases you don't understand. It's nearly impossible to summarize a text unless you have a good grasp of its meaning.
Re-read the text. While reading, write the main idea of each paragraph in the margins. Then, using those main ideas, summarize the essay as a whole.
Alternatively, look for larger sections - groups of paragraphs on a single sub-topic. Summarize each section individually, and determine (and indicate in your final summary) how the sections are related to each other.
If you have trouble using too much direct quotation, try summarizing the main ideas of the text without looking back at the original. Then, when you're finished, check your summary for accuracy and make sure that it is complete.