It's good that you're thinking about college now. If you already know the schools you want to apply to - take a look at their admissions section to learn more about their requirements. Besides that, here are a couple of ways you can stand out!
Get involved in school and within your community - but find leadership roles. You can even start a program at your school - colleges want to see how you've made a difference.
Take pre-AP and AP courses - colleges want to see that you can handle tough classes.
Start building relationships with your teachers (or boss) so they know you as a person rather than just a name - their recommendation letters will help the admissions team get another perspective on you.
Get a job - colleges want to see if you can balance work and school
Your essay is the best way to stand out - I know that won't happen until your Senior year - but you can start jotting down experiences - so when it comes down to write it, you're ahead of the game.
Keep up with your grades!