What is summary writing? 

To summerise is to express the central idea of a speech or write up.    
Summerising therefore involve writing up the main points relevant to question asked in a given number of sentences. To do this, detain or unimportant citations must be left out for excellent summary

Rules for excellent summary writing

1. All sentences must be in complete sentences, either as a whole or a link to an opening statement.
2. Read the questions before reading the summary passage
3. Read the entire summary passage thoroughly and carefully taking necessary notes and making necessary marking as you do.
4. Mark the parts the possible answers are in the passage(especially the main sentences)
5. Try as much as possible to make the summary in your own words(ie different from that in the passage)
6. List your points co-ordinatively
7. Write your answers only in the required number of sentences (not more, not less)
8. Limit your answers only to information available in the sentences
9. Write short and concise answers using good and simple English
10. Use introductory sentences (preambles) where necessary. Ensure that they flow into the sentences
11. Use preambles only when writing more than one sentence or stating more than one factor.

Things to avoid when writing a good summary

1. Irrelevant/extraneous details such as examples or illustrations
2. Compound sentences (using conjunctions to join clauses to become long ones)
3. Mindless or direct lifting of sentences from summary passage
4. Numbering your sentences/points in words.
5. Unnecessary long sentences
6. Big/complicated words that may distort meaning.