One of the first things to do is an "anatomy of the article" which makes clear what 'primary' and 'secondary' are and how to tell the difference. And what to do with each, how to mine bibliographies, how to make sense of abstracts, how to manage unfamiliar terminology.
There's a sense in which the primary literature isn't written to be read: it establishes ownership and priority for ideas and findings, validates its authors' professional identities, serves as a permanent record of scientific progress. It's read by specialists --and by students who are preparing to become specialists. It's customarily written in a pretty rigid style (generally avoiding the first person, often favoring the passive voice, spending little energy on verbal niceties). Few people read primary literature for pleasure.Secondary literature exists to improve access to the riches of primary literature: to interpret, summarize, adjudicate, review --but primarily for specialist or at least scientific audiences.
Tertiary and quaternary literatures are aimed at wider publics --at non-specialist audiences-- and emphasize explanation using language that goes beyond the code of narrow specialties. Tertiary and quaternary are especially useful in the early stages of exploring a subject.
All of these levels are important resources for a student of a subject, and (1) finding and (2) evaluating appropriate and useful sources will occupy a lot of our time.
Here's an example from Lexis-Nexis of a worthwhile tertiary/quaternary source for one topic.
Find one, then find more using the information in the one
(bibliographies, authors, terminology to add to 'cloud'); the one is,
after all, part of an ongoing conversation. You're trying to pick up
enough to join that conversation.