As you're in your earlier years of high school, you might be trying to optimize what you do to be a strong applicant. I believe it's more important to really find your interests in the earlier years and then hone in on them in 10th-11th grade, rather than just trying to do what looks good. I spent a lot of time experimenting with various things in 9th grade before settling on computer science/robotics as the fields that I really got excited about.
It goes without saying that you should build and maintain your GPA throughout all your years, but if you start out low and improve in 10th-11th grade, that's totally cool as well (colleges love to see improvement).
Take a deep breath. You're about to embark on a fun (and challenging) four years. However, it's important to use your first year of high school to just explore. You never know what you may find interesting so get exposed to as many things as you can! Many high schools hold club fairs where each club can showcase their speciality - definitely use this as a way to get involved in things that sound interesting to you. Even if your high school doesn't have a lot of activities / clubs that it offers, you can start your own or find one in your city and join that (check out the Extracurriculars guide for more options). If your school environment isn't the most conducive to holding clubs, try finding other students in your city who may have similar interests to you and start something together. There are tons of national organizations of which you can open a local chapter.
Start going deeper in the things that interest you. Maybe try to get some leadership positions in those clubs. Participate in activities outside of school related to them, such as competitions, fairs, or showcases. Check out the Extracurriculars Guide linked below if you're having trouble finding things to do.
This is the most important year to really hone into what you care about. You'll most likely take your SAT/ACT and SAT Subject Tests this year. Challenge yourself with more advanced classes (like AP/IB/College courses if your school offers them). Try to see if you can participate in more competitions or be more involved in the clubs you picked in 9th-10th grades. Find those teachers who you work well with and who know you well for your letters of recommendation. Spend the summer working working on jobs or internships (check out the Productive Summers guide below).
We've created some guides that we wish we had when we were in high school to even know about the vast variety of opportunities. As always, feel free to ask any questions here, or on any specific guide. Our community of mentors from many of the top colleges are here to help you!