How can I start getting involved in extracurriculars in and outside of school?

I'm a freshman in High School and I don't play any sports nor am I in any clubs or activities that the school offers, but, I want to partake in a few not only so that my extracurriculars aren't blank leaving high school, but also so that I'm able to get more involved in school. The problem is, is that everyone has already made their own clique school club-wise so it's hard to get involved or participate in a club when I'm basically walking in toward the end of the year knowing absolutely nobody. How can I start to get involved in these clubs? I don't want to be awkward. Also, would no extra curriculars for freshman year look bad when applying for a university? I slacked last semester, finishing with a 3.8, and I wanted to get my gpa as close to a 4.0 as possible so that I have a shot at an Ivy League, but I know that this will be nearly impossible without impressive extracurriculars. Overall, how can I get involved? Without feeling like an outcast joining a club full of people who already know each other, of course.