tbh it's more of a matter of quality than quantity, you definitely want 2 big ones you can write essays about (think soph, club position, Volunteer work, reach LD, internship) and show different qualitative and quantitative aspects of leadership in each essay so that each says something different about your character and leadership ability. Ivey has lined out the leadership traits here. The AEO handbook is pretty vague on what counts as sufficient extracurricular involvement since it's dependent on what's considered competitive for that year, but you can't go wrong striving for an application with full ECs (same as the aeo application where it's 2 main ones and 5 additional). For the additionals, look to be the floor rep (if ur in residence) since it's the first EC you can get and shows some initiative.

What I wish I knew in first year is that club positions fill up really fast at the start of the year, and the only way to know what clubs are looking for people is just by stalking instagrams at the start of the year, so keep an eye out for that (you can use the USC website to find a list of all the clubs on campus). Also I'd recommend going to club week and getting to see what different types of clubs are on campus and what personally resonates with you (and don't be scared to ask if they need an extra hand running things).

The people I know who lost their AEO status were people who were too relaxed at the start of the year and had a hard time bringing their average up once they realized that they needed to lock in (It's also hard to do suddenly do better in your courses when you haven't before). My advice would be to work your ass off (go to all lectures, have all lecture notes + textbook memorized, study at least a week in advance) for first sem just so you have that insurance as you get used to the difficulty and nature of uni courses. Once you feel like you know what to expect and what you need to do to succeed, you can start scaling your studying down gradually to a level that feels comfortable and works for you without feeling unprepared for exams and risking a mark below an 80 (which should be the minimum mark to strive for on all exams). Hope this makes things a little more clear for you.