When searching PubMed, look for icons that indicate free full-text is available for the article.
Citations to articles available via PubMed Central, a free full-text archive, will include an icon: 
Many records in PubMed will include an icon from the publisher. Sometimes this icon will indicate free, full-text: 
If the record includes an icon, always click on the icon to see if full-text is available. Sometimes, the full-text article is freely available at the publisher's site, even though there is no indication in PubMed. Click on the previously described icon, or the DOI (digital object identifier) in the article record to access the article at the publisher's site.
Install a free extension, Unpaywall, in your Chrome or Firefox browser. If free, full-text is available, a green unlocked padlock icon will appear on the right side of the browser screen. This tool may not be 100% accurate in identifying articles that are freely available, but it is another visual cue that an article is available.
When you have Unpaywall installed, if you find an article at the publisher's site and full-text is available, you will also see the icon.
When searching for articles, Google Scholar can be used as a supplement. Unlike PubMed or other databases, there is no quality control in terms of the content that is retrieved in a search. Results may include citations to journal articles, books/book chapters, conference papers, dissertations, or scholarly work that has been deposited in institutional repositories. Evaluate search results carefully.
A useful feature of Google Scholar is there may be full-text links to articles that may not be reflected in database searches in PubMed or other databases. Look for HTML or PDF links to the right of the citation.
The McGoogan Library of Medicine at the University of Nebraska Medical Center offers an interlibrary loan service to the following users: "All UNMC faculty, staff, and students can request materials through this service. Employees and physicians with Nebraska Medicine and Children's Nebraska can utilize interlibrary loan services as it relates to their work. Other groups that can use interlibrary loan services include UNMC alumni and Nebraska professionals in need of health sciences-related materials."