Really good website to help you start planning: Café College - click on the freshman link
Pick challenging courses
Remain in challenging courses ALL YEAR (don't get a schedule change just because it's hard)
"Learn how to learn"
Understand Rank and GPA - both are very important and both begin your first day of high school!
Be involved - clubs, sports, community. See your counselor to get an activity log to track all the extracurricular things you do
Begin your resume