As you begin to locate information and resources that look promising, you need to evaluate the articles and documents to determine the credibility, reliability, and usefulness to you.
Your literature review search should be comprehensive so you can conduct a literature review that is highly relevant, selective, and critical. It is possible that only a few resources will be highly relevant to your topic and many others will only be tangentially relevant.
Keep a research strategy journal / results journal
Track search terms and related terms, search strings, databases searched (noting which search strings you used), and general result notes. Update these sections as you go along. Searching is not a linear process.
Read with purpose
Read the abstract. It should contain critical information about the study, its purpose, the methods used, and major findings. Also, scan the introduction and conclusion.
Summarize the major concepts, conclusions, theories, arguments, and methodologies
You may find it useful to set up a table (see the Spreadsheets/Matrics tab for Excel and Word templates) to easily identify major concepts, conclusions, theories, and methodologies from each article. You can also use citation management software to organize your articles, track the copy locations, tag them, and create reference pages with ease. See the Zotero tab for more information. Tagging can be quite powerful - you can tag methodologies, databases, authors, and so on.
Also, ask yourself: How is this study similar or dissimilar from other studies? Are there other studies using similar sampling and methods? Are the findings consistent? Are the data collection methods and analysis valid and reliable? What theories are authors using? How are the studies organized? Are there non-textual elements? Are the authors citing other studies that need to be located?
Place the works into context. Show relationships between the different works. Reveal gaps. Locate your own work within the context of the existing literature.
Go further
Consider whether or not your sources are current. Mine the references page for additional sources.
Make life easier for yourself
If you do this work of documenting what you are searching for and organizing what you find whether it's on paper, in a spreadsheet, or in citation management software, you will make your life so much easier when it's time to write your literature review.