lots of research, though that might not appeal to the less light-inclined of us. initially id classpected myself as a mage of light since i kept getting light on the aspect quiz, but as i've grown older my aspect has changed with more introspection. it really is a hugely introspective process if you want to get one that isn't just a surface level vaguery of your movements through life and personal aesthetics.

a good way to start is just by digging up old quizzes-- there's one lying around on an old tumblr blog that uses the MBTI and enneagram, as much as those are... kind of bullshit pseudoscience they can clue you into some things. i'd also recommend reading up on anything particularly resonant-- i've read a stupid amount of writings on mages within homestuck. a good starter resource is dahniwitchoflight on tumblr, since they have analysis on pretty much every classpect combo. if you're still interested in diving deeper after that:

ouroborista's treatise on classpecting (https://ouroboros.cafe/articles/Treatise_on_Classpecting.pdf) is a very well-written document & argument towards certain class pairs & has some REALLY good stuff on how aspects and class interact with one another.

dewdrop's classpect brochure (https://www.reddit.com/r/althomestuck/comments/1kjmtuk/classpect_brochure_181_nicertolords_edition/) may eternally be a WIP (or maybe i'm just bad at using reddit) but is a super hard hitter re: classes. worth a readthrough and also has discrepancies if you're tied between two (or three, or four) classes.

ultimately, no one source is going to be perfect. don't take anyone too seriously, since at the end of the day its a mythological role for a video game in a comic, even if it can be used as a tool for introspection and social understanding. fundamentally, we construct our own canons, and it's best to come to your own conclusions if it really matters to you. look at the comic! try your own analysis! throw spaghetti at the wall! i personally understand maids & the breath aspect much better just by virtue of Really Liking the Crockerberts. have fun!