Hi,
Think of an abstract; it synthesizes the article by assuming what is the most vital information, and so should a summary. In other words, introduce the aim and purpose of the article, mention the most important findings, and then go on to discuss the problems/information/results/definitions etc. that you consider as most important. That way, the reader will get the fyi of the text without having to read it themselves, which after all is the point of summarising.
Furthermore, it’s important that the reader follows the “red thread” through the whole summary, as well as the cohesiveness in terms of content is important.
