Key points to consider:
Perhaps the hardest part of starting is deciding whether to start with books or articles.
Articles are not just shorter versions of books; each serves a different scholarly purpose.
Articles are argumentative, narrowly focused, and tackle very specific issues.
Books are also argumentative, but have a much broader scope and often provide contextual information absent from articles.
Chapters are often article length and are also narrow in focus, but unlike chapters, are meant to be read within a larger context.
Some fields, like Philosophy, are article heavy. Others, like History, are book (or "monograph") focused. And to add to the confusion, disciplines like Education or Political Science are about evenly split between articles & books.
When deciding where to start, ask yourself: "is this topic broad enough that it would be covered in a book, or is it narrow enough for a journal article?" This will dictate whether you start in a database or in the library's book catalog.
Why do we use books sometimes instead of articles? What is the difference between a chapter and an article, since they're about the same length? Why isn't an encyclopedia article considered a peer reviewed article, and why isn't an encyclopedia the same as a book?
Each format has a different function, different scope, different purpose. Know this helps you know where to start your search.
Every type of scholarly source has a specific purpose and scope, and knowing what each publication is meant to do will help you know where to start. The general types are:
These works will often contain Handbook, Companion, or Dictionary in the title.