What are important factors in accepted college applications to the Ivy League?
Good question. While I can't personally speak to the Ivies in particular, here are some things that most colleges and universities (including, to the best of my knowledge, the Ivies) look for. They want to see someone who can do well in a rigorous academic setting, while also adding something to the community. With respect to the prior, make sure that your grades are good. They don't need to be perfect, but good enough. How good depends on your strengths in the second. If you haven't already, get involved in extracurriculars, be it student government, a sports team, an academic team, volunteering, or whatever else piques your interest. There's an age-old debate over quality vs. quantity, which you'll have to figure out for yourself based on your interests. In all of this, make sure you can explain how you stand out from all the other applicants.
One last thing. Please, please, please carefully consider why you are choosing the Ivy League specifically. It is a popular household name, but it is not for everyone. Many people (unfortunately I cannot think of examples right now) go to them and end up miserable because it's not what they really wanted, they only went because they felt pressured to or was attracted to the name. So ask yourself what it is you really want, and whether the Ivy League is really the best to be looking at. For example, recently, Ronald Nelson turned down every Ivy League school in favor of the University of Alabama because he would have accumulated a lot of student debt by attending an Ivy League school, whereas the University of Alabama gave him a full scholarship (here's the article I found if you're interested: http://www.businessinsider.com/ronald-nelson-turned-down-every-ivy-league-school-for-university-of-alabama-2015-5)
Best of luck, and let me know if you have any more questions!
As an Ivy graduate, though many years ago, I still very clearly remember my application process and...my acceptance letter...for the record so does my Mom :)
I think there are a couple of factors that were helpful. My interest in the engineering program, my grade history meaning what my grades were over time, particularly in high school, my essay(s), the extra curricular activities I participated in and my role in those activities. For example leadership roles in student government.
If you think about the application process, whether it is for an Ivy or not, colleges/universities get excited about incoming first year students because of the "freshness" that they typically bring. The first year student...their open minds, combined with their view of how to make things better. Their desire to learn and succeed...a certain vibrancy that first year students bring where they use their "we are capable" and "we can make positive change" attitude...a large part of those attitudes and beliefs are brought to college campuses and in many cases, those campuses are the better for it.
I share this point of view because as aspiring students put their materials together for their college applications, any way that the student can demonstrate their positive momentum can be a very positive appeal to college/university acceptance.
Hope you find this answer helpful and best of luck to you!