Some time ago I made a list of things not to do in YA anymore. I've done some of them before myself. No more..
1. No more girls who listen to The Smiths. No references to The Smiths at all. Even if the book takes place in the 1980s.
2. No more references to Salinger (this has not been as common a thing in YA since Twilight took over, really - may be time to change this one to "references to Jane Austen or Romeo and Juliet").
3. No more geeks who dream of hanging out with the "popular kids." Nobody likes popular kids. I have no idea why people call them "popular." They're not.
4. No more main characters who want to be writers.
5. No more evil cheerleaders, even if it IS true to life. May still work if they're zombies or something, though. I HAVE always wanted to do a book called "Pushing Cheerleaders Down the Stairs."
6. No more using "psycho girlfriends" as a comedic device. Psychotic girlfriends are no more "funny" than douchebag would-be rapists are "romantic."
7. No more listening to people who say you should never mention pop culture in a book. The REAL rule is "never use pop culture to show readers how hip you are." Every classic book I can think of mentions pop culture of the day, and when I pick up a book from the 1960s, I expect them to talk about the Beatles or something. Sure, there ARE readers who want every book to seem like it might have taken place in the previous couple of weeks, but do we really need to aim every book at THOSE people?
8. No more trying to set books in the 1990s, even though building a plot is a LOT easier if no one has a cell phone. Seriously - go back and read some books from the 1970s-90s and see how many of them have a plot that would have been resolved by page 10 if someone had a cell phone. Even now, I have to have characters lose theirs occasionally or something, or there's no reason to go out on the road and have an adventure. Let it be a challenge to you.
9. No more dystopias without flying motorcycles. Because flying motorcycles are awesome and I don't want there to be a future that doesn't have them. Really, any dystopia set in a world that doesn't look like a Meat Loaf video is just not okay with me.
10. No more male leads who are that one character that Michael Cera always plays. You know what I mean. Good natured guys who read a lot of comic books and dream of dating a girl who listens to the Smiths. I want more male leads who AREN'T just killing time until they go to college and become a software engineer. More guys with poor grammar and a dim future, please. A while ago I re-read a 1986 book called Dear Bruce Springsteen. The down-on-his-luck D-minus student who narrates it reminds me of LOTS of people I've known in real life, but I can't think of a single other narrator like him. This is the kind of book that makes me want to start a blog on 70s-90s books that we'd call YA today.
I WOULD have a thing about "no romantic interests who act like rapists," but this is really a list for ME, and I wouldn't do that, anyway. It's implied in #6. I did have a book where the BAD guy was a vampire who tried to convert (basically rape and kill) the narrator against her will; it stunned and disgusted me how many bloggers said that they didn't understand why she didn't like that guy, or said that if they could date any character in the book, it would be him. Maybe the publisher should have let me be more explicit about the conversion process worked, though saying it's "similar to sex, but not exactly the same" and having it kill you and turn you into a member of the walking undead ought to be enough, really.