Проблемы с грамматикой, проверьте на правильность составления и употребления времен.
1) Then, working in
enterprises of different activity scale and structures I have developed a lot
of quality. Such as, the ability to take the necessary decisions in difficult
situations and finding a common language with different people.
2)In my opinion, people
should not stay there, and continue to improve themselves.
3)After graduating from
high school, I had entered in the ..., at the Faculty
of..., which I graduated in...