1. Conveniently absent parents. Ah, the good old tale of the workoholic. It's the oldest trick in the book. Authors must have just been like "Okay, so here's the situation. We need this teenager to have unlimited access to a house, car, and money, but parents don't get to be involved in this dystopian rebellion. We either kill them or give them a job that requires an unrealistic amount of business trips."
2. Manic Pixie Dream Girls. Listen up. Love interests aren't going to fix you. Female characters are not there to be sexual awakenings, pieces in a love triangle, or muses. They're characters that should be as complex, developed, and interesting as any other character in the story. So don't use them to fuel the crapshoot that is the protagonist's timeline to manhood.
3. Body transformations that "fix" the character's life. Don't try and tell me that a makeover was the only thing that impacted the character's story line. It's not the source of the problems in their life, and I can guarantee you there are far more unique ways to develop a character than having them drop 40 pounds and get a haircut. This is tired and impractical, so just let this die.
4. The broody bad boy. YA books gave me an unrealistic expectation of relationships. They made me legitimately believe that teenage boys wear leather jackets, smoke cigarettes, and read classic literature at 16. Guess what, honey - he's only reading To Kill A Mockingbird because he has an essay due next week, not because he's at all interested in its message. And why do they always have a mysterious accent? What's that even about?
5. Insta-love. This disgusts me. If your entire love story unfolds within a weekend, I will be exactly 0% impressed. Give me friendship. Give me fights and angst and tension and memories. If you want me to feel the love, then at least put some effort into its foundation.
6. "I let out a breath I didn't even know I was holding." (Next on "The Most Overused Line in All of YA Lit"...see also "I was the chosen one".) Next book that contains this line is getting tossed right out the window and into a firey abyss.
7. Stereotypical antagonists. I'm not asking for much, alright? I just mean that it's too easy to just have an evil person be evil for the fun of it. Give them a reason. I need some substance. Be it a unique backstory, a tragic plot twist, or literally anything other than "evil by association/because I needed a villain".
8. Absolutely zero character development. Let's get one thing straight. People change. You can't start a story (especially a series) with a character who has certain traits and then make those be the only traits they have from start to finish. For example - don't make the joker of the story a two dimensional comedic relief tool. Develop them. They deserve a backstory, a history, and an evolution. It's annoying and boring to have no reason behind a character's behavior.
9. Unrealistic settings. If the setting is a high school, make sure the high school actually functions like a high school, alright? There is no way these teenagers have enough time between classes to fight off demons or save the universe. You barely have enough time to use the bathroom and get your locker, let alone break the law or save a damsel in distress. I'm not asking for a boring structure or anything, but honestly. Don't push the envelope so much that it bursts.
10. Love triangles. Don't get me wrong, I'm a sucker for relationship drama. But this love triangle situation has gone too far. Why is it always one girl having to choose between two guys? Where's the book where she rejects both of them and decides to start a business or marry her best girl friend or something? Where's the variety? There's so much that can be done with this, but it's become so heteronormative and redundant that it's losing all the appeal.