Most lists fail for the same reason: they are built from names instead of criteria. Start by writing down five things a school must have and three it must not have. Budget ceiling, distance from home, size, a specific program, a climate you can live in. Only then open a search.
Three tiers, not two
Sort candidates by your odds of admission using the acceptance rate and the school's middle-50% test or GPA range. Aim for two or three likely schools, four to six matches, and two or three reaches. A likely school is one you would attend without regret, not a consolation prize.
Test each school against the criteria
Open the profile and check each must-have. If a school fails one, take it off, however well known it is. If the list is still over twelve, cut the schools you cannot explain in a sentence.
A good list has no school on it that you would be disappointed to attend.
Visit before you commit the list
Use the campus visit checklist on at least one school from each tier. Visits change lists more than rankings do.