Short answer:
Come up with new original ideas.
Long answer:
The easy way would be telling you what tropes you should avoid, instead I'll give you a bit more difficult, but much more useful thing: a short lesson about avoiding cliché storms.
Study the genre and observe which tropes are overused, by playing them straight. Or in case of cliché storms, painfully overused and still painfully played straight. Then we arrive to step two, when we have to decide if is it a necessarly weasel (an illogical trope necessarly for the genre) or not. If the're not, you even can avert them, but the key is not playing them straight. You can do anything with them as long as you keeping the genre.
Good luck with the writing! School settings are very prone to clichés (especially if you're doing some romantic side-plot in them), but everything can be done good.
So.... I have this idea for an unusual wizarding school, but, like with my magical girl idea (sort of) it's a school that teaches how to use a form of magic called artisancraft where magic comes from art, music, drama and writing/words.
The protagonist is a new girl who is decent at the artistic part but struggles with getting a hang of the magic part. She has relatives that are expecting her to be great and powerful, for the sake of the family name.
The school itself is unusuual in that it's also a training academy for the a hidden community of 'artisans' teaching them and using them as 'Royal Scout trainees' to protect the crown.. Huge projects are spy type missions touted as 'field experience.'The administration of the school is an antagonist in itself, they're secretly against the royal's they're meant to protect and have divided loyalties.
The plot I have in mind for the story is basically a huge test for the protagonist who's an 11-13 year old girl. (It's explained that the people within the mage /artisian community have a higher opinion of their youth's capabilities than most school. ) When she has a hard time accessing her magic, and fails at a few minor projects, the scheming head boy tells her that if she doesn't pass her upcoming group project she'll be expelled for poor scholarly performance. So with the help of her group mates she has to figure out her powers and be able to hold her own in a secret mission.
For the school part of the story I want to avoid too many high school cliches. The main characters aren't too concerned with popularity contests, there isn't much of a romance sunplot, and while they're are bullies and mean kids, they're not the main problem (although their bullying doesn't help). The main 'antagonist' the the protagonists' own inexperience. (Though a formerly expelled student out to ruin it for other kids is a minor roadblock.) What High school cliches should I avoid?
edited 20th Nov '13 11:15:37 AM by JewelyJ