Have no shame if your favorite books are popular books like Harry Potter or The Hunger Games. Don’t listen to people who say a book isn’t any good; read it for yourself, you be the judge. Find the little nuggets that will help you learn to write better. And, likewise, don’t you dare put yourself through the disastrous experience of being forced to read something terrible just because it’s supposed to be a ‘classic’ or because someone else has declared all non-readers of the book uneducated.
It’s like what Bill Hicks said years ago, “You‘re right! You‘re right! Not those fuckers who want to tell you how to think! You‘re fucking right!” Read it, then decide. Is it good? (does it make you laugh? Is it suspenseful? Do you like the characters?) Or maybe it’s not. If it isn’t, then who the fuck cares whether it’s written by Jane Austen or Jane Doe? It still fucking sucks, right? And, you’re entitled to believe that. Just don’t put someone else down if they read the same book and think it was written with Merlin’s magic jizz.
Be adventurous, try all kinds of writing. But, don’t think for any solitary second that good writing is determined by popularity, whether that be low-level (like most ‘literature’) or high-level (called ‘popular fiction’). If you like it, then it’s good and the world needs more of it. So, get studying the texts you like (not the ones you’re supposed to like) and figure out why it works. Then, get writing.