Getting the right moves is tricky, because they create play: each move is a tool and as they say, give someone a hammer and everything starts to look like a nail. Start with two questions:
- What is this game about?
- What do the characters do?
Your game's about high school, so start listing things that happen there: there are lessons, lunch breaks, rivalries, friendships, a lot of teen romance, people discovering what their principles are and so on. If you base a move on any of those, then that's what the characters' will do, because that's the tool the players have been given.
Say you make a move called
stand up, where you stick to what you believe to defend yourself or another: given that move, players will look for situations to use it, especially if the stat they roll for it is highlighted that session and they mark experience for just trying.
What I've done before is to scribble down notes about the kind of situations I would expect to see in that setting and the kind I want to see in play, then pull the moves out of that; next, shape the outcomes of those moves so that the drama always moves forward in an interesting way, e.g. in my superheroes hack, the moves allow you to fight the villains, but they will rarely be caught even if they lose, because the outcomes the players choose from make that a much bigger deal than just letting them escape to fight another day.