She opened the curtain and looked through the window before shutting it immediately.
This sentence should be revised to include vivid imagery. Imagery is the creation of an image in the reader's mind through words. Every reader creates his/her own image from the words on the page. The more vivid the imagery the more the image the reader creates is similar to the image other readers create. In this sentence, we don't know how she opened the curtain: quickly, slowly, impatiently, secretly. We don't know if the window is clean or dirty. We don't know what the curtain looks like or how heavy it is. All of these details could be added to create a more vivid image.