I’m currently A sophomore in a public high school in Austin TX ranked #7 in the state, and Stanford is my dream school and, I would like to know what could increase my chances to getting into the Stanford, I’m an a student and I take difficult courses, I work at YMCA and I do a lot of community service.
Take a look at this year’s decision thread to get an idea of what kind of applicants were accepted.
My friend was accepted to Stanford RD, and in addition to being an excellent student, he was VERY passionate about music (so passionate that he did world tours and played on every continent except, obviously, Antarctica :D). He is absolutely positive that the adcoms saw his passion and accepted him as a result.
That being said, I’m sure you don’t have to take worldwide tours or anything of that sort, but pursue your passions!!! This will help you tremendously.
Invest time in the causes you care about, rather than “participating” in many extracurriculars in which you do not or cannot invest that much time. 
I agree with Amar. Excel in something you are passionate about or at least find a way to stand out. The traditional advice of showing you are well rounded student is of secondary importance. Some students join every club possible and participate in as many sports as possible. That doesn’t make a student stand out. Almost all students join clubs and many play sports. Also with community service, it has to be something substantial. The majority of students will claim on their application they did some community service somewhere during their high school years.
Please do not fixate on Stanford. I know it sounds trite but follow your interests, take risks and find out more about yourself every day. Then you might find out what colleges would really fit you the best.
And if you are in the high school I think you are in, it’s very very competitive. Yes, I’m in Austin too. Don’t get wrapped up in the admissions game there. It gets brutal there. It’s not where you end up at college but what you do once you get there that will define you. Good luck.
Best way to ensure getting in: play a sport. Other than that, the best advice I heard while I was applying is be passionate when writing your essays, they have a lot of extremely intelligent students applying so the essays are one of the best ways to set yourself apart and show your uniqueness.
The bulk of your ability to get into a school like Stanford is out of your control: either you’re the sort of scholar that is viable or you’re not. Your wishing it to be won’t do.
The people I know who were successful at getting into top schools got into them as mostly a side venture. They were already on a trajectory for greatness and their energy and drive dripped off of them – and it didn’t matter what college eventually admitted them. They didn’t care to be perfect because that was never their goal – they were hungry and that hunger drove them. They didn’t sit around as 10th graders dreaming of a school with an admit rate like Stanford or Yale or MIT – because that’s frankly foolish and illogical.
If you happen to be blessed enough by the time you’re a senior to find yourself having accomplished a ton, then YES, you can improve your chances by writing compelling essays and getting top LORs like post #6 said.
But to be frank, I never run across top school admits who “dreamt” of them as 8th 9th or 10th graders.