In 2005, I finally joined my school's famous orchestra.which I had heard so much about.
It seems a bit wordy. I think this could cut some words out and still retain the same meaning - correct me if I'm wrong though...
Initially a third violin, my conductor, recognizing my dedication to practice, assisted me in honing my talent.
No, no, no :) That is incorrect use of hyphens. You generally use hyphens to express a (completely) different thought:
And you spread butter on the - Oh my god! The toast is burning!
Like that. :)
assisted me in honing my talent
Seems a little wordy here too... how about just simply: "helped me hone my talents"
In less than a year I was handed sheet music for first violin.
Very nice! :)
and doingtaking solo exams
To me, "do" is an over-used and generic word. When writing essays, try to find specific (perhaps even specialized) words that describe what you want to describe. :)
very enjoyable, stimulating, and critical
learnt
This should be "learned"
which have also developed a great sense of commitment within me
A little awkward to me... how about:
"through which I developed a great sense of commitment" ?
It is the orchestra that exposed me to many people, places, and ideas I now appreciate.
It seems like you make a habit of this. :) Remember that if you are listing more than two things, you need a comma before the "and" also.
This essay is ok. From what I've learned, though, I believe you should focus more on a specific experience and elaborate how, specifically, it affected and changed you. Right now, you are saying that the orchestra was stimulating and critical to you character development, but I don't see specific details that support that. From the above suggestions, I've cut a few words out, so I think you can add the details while still maintaining the 150-word limit. :)