Keep up with the newest literature on a subject of interest by using this strategy: locate the most important previously published papers and then track where those papers are being cited, i.e. included in the references of other papers. You can do this by using the citation searching capability of Web of Science, Google Scholar, and PubMed. See the images below for details.
Both Google Scholar & Web of Science allow you to create alerts for your searches or for citations, which will result in emails to you when new articles fitting your search or referencing a particular citation are added to their databases.