[FSU’s Common Data Set](Office of Institutional Research - Florida State University) describes what criteria are considered and how they are weighted.
Course rigor is #1. FSU wants to see AP/IB/Dual Enrollment/etc classes. Second tier are GPA and test scores - how you do in said hard classes. Extracurricular activities are a third tier consideration. They’re important to have some, but unless you’re borderline, they probably won’t factor into the decision.
Intended major isn’t going to determine whether you get in or not. A high percentage of students switch majors, plus you aren’t formally admitted to any program when you’re an incoming freshman.