Note that the articles indexed in these databases may not be freely available. Try Unpaywall for legal, free access to articles.
The National Guideline Clearinghouse went offline in July 2018, and there are a couple of replacements in development. Both links below are free, but require registration to access clinical practice guideline summaries.
Open access resources are free to access without any subscription fees. There are:
This area is growing and changing rapidly. Evaluate open access journals carefully, as some are considered predatory and unreliable.
Your hospital will have information resources. Look for a hospital library and hospital librarians!
Professional organizations will help you connect with other nurses in your field, and often provide information resources, too.
Consider using the CRAAP Test to evaluate sources.