While there is no magic formula that all schools follow in the admissions process, most schools look for similar criteria.
Most schools rely on your academic record to determine whether to accept you into their programs. Look in the school's catalog or on their website to find whether your high school coursework meets that school's minimum requirements.
More than the minimum
You may find that three years of math, four years of language, and two years of science are needed at a liberal arts school. But if you are applying to a university's pre-med program, you may be expected to have at least four years of math, four years of science, and three years of language.
Schools also evaluate your choice of electives. They look for evidence that you made the most of the courses at your high school. Choosing an additional course in math, science, or your field of interest may not only increase your knowledge but may also place you ahead of applicants who have the minimum credits. So, if you can handle it, think about taking an additional class instead of adding an extra study hall to your schedule.
While academics are important, schools turn to your non-academic achievements to get a better sense of you as a person. This is where your clubs, leadership positions, and community involvement will help. Schools like to see evidence of your ambitions and early steps toward realizing your dreams.
Schools generally look at the scope and depth of your experience, rather than relying on just the numbers. So don't just compile a list of a dozen or so clubs and organizations to impress a school.
It's better to show you were truly committed and successful within a few organizations (at school or in your community) or worked hard to develop a skill (such as chess or playing the piano).