Let me make one thing clear: that is not a bad reason for doing something. Not everything has to have a super-duper deep reason for happening. That green light Gatsby's always pining over could actually just be a green light. Maybe green's just his favorite color! If your reason for putting something in your book is "because I think it is cool" that is not a bad reason. That is a totally acceptable reason. You just need to own that.
I say that because it is important to do things not just because they're cool. If you just took a bunch of cool things and throw them together, well, you probably won't have made anything very cool. If you like dragons, spaceships, robots and wizards, and want to throw all those things together into one book (hint hint my WIP) that's awesome, but you have to recognize that you can't just throw them in and hope that they work. If there's no cohesiveness with all these drastically different elements, your story will feel inorganic and at best (or worst), people will think it is satire.
Let's bring this back to spooky quotes and chapter headings. For those of you who have no idea what I'm talking about, maybe because you just happened to read books that didn't do this, a chapter heading is something like:
Red Star rises
Our day of doom
Too late to repent
Our lust for power
The Book of Armageddon, Songs of Sorrow, 4:17
The plot was all plotty with the characters doing something and some spookiness was totally drawing you in and making you ask questions about what would happen next and-
Okay, you get it. Now, the little "poem" is actually taken from my WIP. The text... not so much. This is a pretty standard chapter heading. Sometimes you'll see others that are just quotes from some historical figure in the world, or some mysterious actor somewhere else in the world you just haven't seen, there's a lot of variety.
They're all cool, and if you're writing these into your chapters, that's great, but I want to make sure that you do this right. Doing something just because it is cool is fine, but what's better is doing something cool and making it work. The Name of the Wind is a book filled with classic fantasy tropes, but Rothfuss didn't look at his book and say "im stealing X, Y, and Z because they are cool" he said "I'm stealing X,Y and Z because they are cool and I'm going to do this different thing with them!" He owned the fact that much of what he was working with had been seen before, and didn't let that slow him down. He didn't worry that someone might look at his book and say "this is just grown up harry potter" because you know what? Awesome. Grown up harry potter is awesome.
But lets get some specifics, and try to keep me from ranting. In my mind, there's a few real reasons to use chapter headings. If you can't fit yours into this list, don't worry, but do think about why you're writing in these cool quotes.
1) Adding to the world: Using your poems and quotes and whatever to give the reader a better feel for the mood of the world at large. The kind of songs people like to sing, the books they read, the important people in this world's history. This one is the most basic, IMO, and also one of the best. You can be pretty random with what you do, so long as you maintain the theme of adding to the world at large, and not to the plot directly.
2) Building the Plot: In Brandon Sanderson's the Way of Kings, each chapter starts with a quote and a semi-mysterious notation. You aren't sure what these have to do with anything, and they seem like just sort of cool visions, until you get to the end of the book. You aren't given any real answers, but you know the plot is deeper and you feel like you understand more because of what you've been reading up to, even if you didn't get what the quotes were talking about at that time. When you're using your headings to build up the plot, you can do some worldbuilding in this too, but once you start making plot related headings, the reader is going to expect that every heading relates to the plot.
3) Unrelated sayings: This is the most blase of the choices, but I've seen books where the authors just put cool quotes about basically nothing at the top of every chapter. Usually this is a lot of "deep thoughts" the writer themselves had, or less used quotes that they found and want to repurpose. Don't be afraid of being the person who does this, but remember that some people aren't going to enjoy "purposeless" quotes.
Those are the three uses I can think of for chapter headings, and there's only one rule that I live by with them: Be Consistent. If you are choosing to add to the world with your quotes, but not the plot, make sure you don't start throwing in plot hooks. Likewise, when you decide to use your headings to advance or introduce a background plot, don't just have one that's an advertisement for a tavern somewhere. If you do switch between these, make sure that you do it immediately. If your first chapter starts with a plot hook heading, and your second is a worldbuilding and your third an unrelated but cool in-world saying, your readers will be prepared to just accept whatever you give them. You just don't want to do five plot hooks in a row and then throw in a random saying -- the reader will have been expecting a plot hook and unlike many other places where it is a good thing to buck reader expectations, the chapter heading is a place where I believe consistency is key. Reading those headings is actually one of the most fun things about a book, and I'm a sucker for well written ones.
But maybe that's just me.
Chapter headings can be a great way to give your readers a greater sense of mystery or a greater sense of immersion, or just a quick laugh. They're powerful tools, if used properly. Just remember what it is you set out to do, and what purpose your headings serve. And whatever it is you're doing, own it. No matter how stolen or ridiculous or whatever. Own it. Make it yours. Even if that thing you're owning is a haiku about demon sex positions that start every chapter. It's all yours.