As others have said, it's more important to pick something you like than something that you think will "look good" on your "resume." If you enjoy an activity, you're more likely to get more deeply involved, which will provide greater opportunities to do more and to lead.
As a freshman or even a sophomore, don't be afraid to try a number of different things, both in and out of school. By junior year, you should settle on the 2-3 that have been the most rewarding and seek ways to lead. That doesn't necessarily mean you have to be the club president. You can lead a project, a fundraising drive, a membership drive, et.c