One commonality across most practices for lawyers is the amount of time spent reading and writing, especially in your first couple of years of practice. One way to prepare yourself is to read a lot. If you naturally already like reading, challenge yourself with your reading materials. Read things that don't particularly interest you. Read things that are complex. Then practice explaining complex ideas to different audiences (friends, family, classmates). These are some baseline skills that will help you at this stage in your life. You will add additional skillsets in college, law school, and at your first job.