Start at the ends. Important information is usually concentrated in the abstract, introduction, and conclusion of the piece. From this quick scan, you can likely tell if this resource is important to your research and merits inclusion in your literature review.
Look for landmarks. Journal articles generally follow a set structure with titled subsections like Problem Statement or Research Methods & Design that allow you to skip to the content you need.
Take notes as you go. While you may remember the central argument or findings of a resource now, after you look through a whole body of research you may lose the nuances of individual pieces. Important things to keep track of may include central ideas, research methods, referenced works, and refuted or counter-argued ideas.