Writing problem in engineering classes

I have a major problem in writing compositions. I always write in an informal way. I believe this is because i got most of my vocabulary from english movies and soap operas, and in movies, people are talking in a very informal way. I pick up those words and i am quite puzzled whether these words can be used in writing compositions. In addition, since my vocabulary is limited, usually i cannot come up with another word to express my idea. So tutors always tell me to write in a formal way while i alway fail and i always cannot get a good grade in writing academic essays. This problem is crucial and it takes time to fix it. But I think i can fix this problem by reading more articles from newspaper and doing more vocabulary exercises. Writing style is very important and the method to improve it is either by learning from reference books or by reading more journals and academic articles. I think writing in a formal way includes using formal vocabulary and writing in formal syle. Articles in newspaper are well organised and have been revised for several times. So articles in newspaper are qualified to be a good example of formal writing in some sense. Reading more articles can give me a good sense of writing so that i can get an idea of what formal writing style is like, and then i can try to improve my writing style. And for the vocabulary, i think doing vocabulary exercises is simply do exercises and memorize more new words. Also, since memorizing words is tough, i can try to use new words everyday so that i can remember new words for a longer time. However, what i have mentioned above are my ideal but not practical solutions to my writing problem (at least not practical for now). I cannot fix the problem in a short time, so i will read articles and do exercises in the future and try to solve my writing problem in the future :P