Is being an artist ,a good extra curricular activity and how to make my way on to top universities?

I'm assuming that top universities to you mean the Ivy League and Standford or similar. I'm also as assuming you already know that a good SAT for those schools is a 1500+ and a good GPA is a 3.9+ Unweighted one.

When you apply to these schools all of them will give you an opportunity to list your extracurricular activities in detail, you awards and honors and your ability to submit an art portfolio. Therefore, if you haven't already you should have a resume of your art achievements. Things to put down on your C.V. for art would be what kind of awards and honors you have won with your artwork, what kind of art projects you have done for yourself and also to impact your community (perhaps you painted murals or created art for publications or public service announcements), and perhaps your paintings have been shown in art galleries or organized exhibitions. If you are a serious painter, you will have examples of your best art photographed professionally so that the admissions office can evaluate your fit within their desired class of Freshman.

Similarly with your writing, you will also document in your application and awards or honors you've received for your writing, a list of publications you have worked on either as a contributor or editor and any examples of writing you have entered in contests or pieces that have been published. Some colleges like Princeton ask you to submit a graded paper as part of their standard application, so you should be prepared to select one of your best examples of a graded paper, something that perhaps you did for an AP/IB or honors English class.

Whether your spike is using your paint brush or your voice through your writing, what all colleges want to see is how evolved is your body of work and whether you show evidence of intellectual curiosity or vitality through your painting and writing.

Some colleges like Brown University are have a dual degree program with the Rhode Island School of Design so you cant apply to both and submit your art portfolio to RISD. These are highly competitive programs and the acceptance rate is like 5-8%. Other schools like Columbia, NYU are in the heart of an ART Metropolis so if you are talented you will always find a thriving art community in a place like NYC filled with galleries, studios and specialty art schools like the Cooper Union. If you are serious about painting and writing, I highly recommend that you apply to schools that are in close proximity to large cities where there is an appreciation for both art and the written word. This is important if you want to be part of a community and participate in that community. If you are painting and writing up in Ithaca, NY, I don't think you'll have the same access to knowing what the pulse if that is of interest to you. I know a painter from LA who went to Iceland for Winter to paint snow and ice landscapes and came back to LA with some incredible looking pieces. Sure she was lonely and isolated from the rest of the world but it worked for her and her personality. Some artists and writers feed off the positive energy of others or like the give and take of exchanging ideas and feedback. Others thrive in isolation. You'll have to decide whether being holed up in Manchester New Hampshire is a good thing or a drain on the soul.

Good luck with your admissions journey.