<p>First of all, have fun! It’s your first year in high school, make the best of it.
Here’s a couple things that I’d suggest (things that I didn’t know two years ago -_-):</p>
<ul>
<li>Join a club that you’re interested in. AdComs like seeing dedication over four years more than just simply joining something in your junior year. </li>
<li>Try to become a leader in some school activity, be it sports or the club that you joined.</li>
<li>Make good relationships with your teachers and definitely your guidance counselor. Tip: if you participate in all of your classes on a regular basis and ask intuitive questions, your teachers will most likely have a higher opinion of you.</li>
<li>Start volunteering at a local facility.</li>
<li>As everyone said, take the most rigorous classes available to you. Even though people may call you crazy and whatnot, you’ll have the head start because you’ll be used to dealing with a heavier course load than the rest of them.</li>
<li>Get enough sleep… The worst thing you can do is to severely deprive yourself of sleep the night before a big exam of whatnot.</li>
<li>Standout in your school! Do something unique!</li>
<li>Keep on top of everything. Projects, homework, your grades, school events, you name it.</li>
<li>Don’t overload yourself with too many activities. Even if you join 5 clubs and volunteer at you local food bank, it’ll look bad to AdComs if your grades start to drop from As to Bs.</li>
</ul>
<p>Final piece of general advice: Know what you can handle and (because you say you are introverted) force yourself to form great relationships with your teachers.</p>