The "token gay" character
The mirror catalogue
Kids or teens who sound like adults
Every setting looks like a postcard
I agree with all of these, but I'd like to add my two cents worth: When all or most of the characters in a story are queer, and no parades or clubs are involved. The Insiders, by Mark Oshiro, is a good example. Three different queer kids take refuge in janitorial closets at their respective schools, only to find themselves brought together by the room's mysterious ability to warp time and space. The book is well-written, and I enjoyed the story, but what made me roll my eyes, was a scene where one boy comes out to his dad and grandmother. His grandmother then admits that she had a relationship with a woman, prior to meeting his grandfather. Is that really the only way that a parent or grandparent can accept their child? By being queer themselves, or having a queer friend/sibling?
Also, The Insiders has a school resource officer named Kwame Mbalia. I don't know if this was meant to be Mr. Oshiro's nod to a colleague, or if it was intended as a placeholder name that didn't get checked, but I find it annoying when authors write characters that are named after celebrities. Or when characters are loosely based on a more famous character or person.