If you have a teacher you don't get along with or don't click well with, take some time to reflect why, and see what you can learn from the experience anyway--- even if you feel like you're not learning much History or Algebra from the person, there may be a life experience you can gain
Figure out a good balance of extra curricular activities-- don't over schedule and spread yourself too thin, but also make sure you are well rounded in which organizations/clubs/teams you join and what you do in your spare time
Go to every school sponsored event you can-- even if you don't have a date ----it's OK to go to the Homecoming dance with a group of girls-- don't stay home just because no one asked you to go---- and be sure to go to the Homecoming game even if you hate football!!------ OK, maybe times have changed-- I don't have a teenager-- but when I was in high school I was glad I went to those things so I don't have regrets of wondering what it would have been like
Take lots of pictures and keep a scrapbook and/or journal. A high school friend of mine recently sent me some letters I'd written to her that she kept for over 20 years. With all of the electronic email and texting, your daughter won't have anything like that to look back on unless she writes things down (or prints out emails to keep). It was so cool for me to read old letters and drum up memories of what was happening back then and who we had crushes on!