It's time to refine your list from "exploring" to "seriously considering." This helps you focus your research and essay efforts!
Run each school's net price calculator. If a school is clearly unaffordable and you're not a strong candidate for merit aid, consider removing it.
Does the school offer your intended major? Do they have strong outcomes in that field? If you're undecided, do they offer flexibility to explore?
Use Naviance/Scoir scattergrams. Remove schools where you're far below the admitted range unless they're important reaches.
Can you write a compelling "Why Us" essay for this school? If you can't articulate specific reasons, it might not belong on your list.
10-15 schools total — enough options without overwhelming yourself during application season.