Every writer has a specialized knowledge outside of writing. Some of us know about animal training, skateboarding, corporate financing, food preparation, running a hotel, astronomy, or pop culture. Whether you do it on purpose or not, your unique insights will worm their way into your writing… and they should! People like to read the details and secrets of unfamiliar professions, and your insider knowledge will bring authenticity to your work.
There are, however, important types of knowledge that could be necessary to your story. Are you writing a science-fiction novel? You probably need to understand the basics of science. Psychological thriller? Historical drama? Existential comedy? Even if these aren’t your usual genres, “big concepts” can pop up in any work of fiction, and you need to be prepared.
Dedicate a bookshelf to introductory reference books, beginner’s guides, “For Dummies” books… there are entire series of books dedicated to teaching the basics of vast or difficult concepts. Search them out, page through them when you’re bored, and keep them close when you’re writing.
Not only are these resources useful for understanding big concepts, but they can be a great source of inspiration!
This goes without saying, but I’ll say it anyway. If you’re writing about a specific concept such as manic depressive disorder, the origin of Hinduism, or a vaccine that will end aging, you need to research these topics thoroughly! Michael Crichton didn’t write Jurassic Park by reading Chaos Theory For Dummies.
In short, be an expert at a few things, but understand the basics of everything.