I think the key to writing well in the dystopia genre is actually having an ideal about society that you want to examine. Like, the whole point of dystopia is to portray a society that looks ideal but really isn't. And you can't explore that juxtaposition unless you know what's wrong with the false ideal, and what the true ideal should be.
Unfortunately, a lot of people tend to approach dystopia as a mere excuse to write about teenagers rebelling against a nondescript 'authority' that enforces Pointless Rule #384 for no discernible reason. Like, everyone who's born with purple eyes has to go to the death camp, and the moral of the story is if you have purple eyes, don't let them send you to the death camp...I guess. =/ Very surface-level stuff...
But even a premise as random and stupid as that can have weight if you actually use it to explore an ideal. Like, what does having purple eyes entail within this fictional world? If it's some measure of 'genetic inferiority', use it to talk about eugenics. If it's a trait belonging to a certain race/culture, use it to talk about ethnic cleansing. If it's a remnant of a race that was already seemingly wiped out in the past, use it to talk about the horrors of war and genocide.
Why are these things considered ideals for people in power, or people seeking power? How can we break down that logic and take a close look at the human frailties that make even powerless people want to go along with it? What kind of world is the MC living in, where simply having eyes that are a different color can dramatically alter the course of their entire life, and put them into a position where they need to demand systemic change just to survive...?
...It's actually not that hard, tbh. ^^; But you have to be willing to take your world seriously and talk about *gasp * POLITICS, at least in a subtle way. And a lot of people would rather not...