I think that the step that is crucial when doing a close reading of nonfiction is writing notes in the margins while reading the text. Thus it will be easier to summarize later.
Close reading may be used to focus on specific skills and ideas contained within a short story or article. The steps to follow in order to close reading are: getting the Gist, diving deeper, and putting everything together.
While reading, you can take notes of the most important facts you can identify in the text in order to grasp the main idea or concept.