I am currently a junior, and Notre Dame is my number one school. What should I do to better my chances of getting into Notre Dame? Thank you 
Maintain a unweighted GPA close to 4.0
Take a very rigorous academic schedule
Score high on standardized testing, preferably a 34 or higher on the ACT
The things you need to do to increase your chances for Notre Dame are really the same things that you should be doing to get into any other top academic institution.
Watch this video
https://www.youtube.com/watch?v=3DQOPx1EGE8
Read through as many threads in the Notre Dame forum on College Confidential as you can.
What GradeDad said.
Also, figure out a way to set yourself apart from the sea of other applicants who are near the top of their class, have weighted GPA’s above 4.0, and score above 33 on the ACT. Honestly, much of your application is already beyond your control at this point – the rigor of the school you attend, the grades in courses already taken and the rigor of the ones you will take this academic year, your general test-taking ability, your position in sports or other xc activities. You have some control over the teacher who will write your letter of recommendation, but none whatsoever over what he/she writes about you. So what is left? Most applicants to Notre Dame and similarly competitive schools don’t have much work experience to list or discuss, but work experience is treated like extracurricular activities and family responsibilities on the Common App. If you have a paying job during the school year, working at least 10 hours a week, that will set you apart. If, instead of taking an internship or serving as a camp counselor or taking summer classes or doing an overseas service trip, you spend your summer working 40 hours a week at a non-glamourous job in retail or food service, you will stand out. Especially if you devote your essay to some aspect of your work experience. My kids and other students in our extended family were able to write about their menial labor jobs and I think that helped them stand out from their peers. It is amazing but true that most kids aiming for super-competitive schools don’t have jobs during the school year, and even summer menial labor jobs are rare.
Of course, you may have something else that sets you apart, so getting a job might not make sense for you. But IMO it’s one of the best ways to move the needle once you are a junior. Younger students have more time to improve grades and test scores, and to find a niche inside or outside school that sets them apart.
Good luck!
Scoring high on a standardized test is more impactfull then GPA, preferably a 34 or higher on the ACT. ND really looks for activity outside of the classroom, not just a member of a club, but the president of one. Founding a club at your high school really increases your odds. They also like consistently, is there a common theme amongst your clubs and volunteering? ND is not impressed by someone who joins dozens of clubs just for the sake of trying to look busy, they want someone who has a “passion” on a subject.