1. Explore (casual web searching)
2. Background (library catalog: books)
3. Scholarly conversations (library databases: articles)
4. Support arguments (source citation)
5. Drafts & revisions (librarians & Writing Center)
PubMed is a great resource, in that it provides up-to-date information on all health-related research being published. That said, be aware that it is an index and not a full-text database. While some articles will be freely available via a full-text PDF link that says Free PMC Article (or something similar), many will not and you will need to seek them out using the CitationLinker tool.