i agree with the others that reading as much as possible and taking in sentence structure, grammar, learning new vocabulary words, and seeing words spelled correctly on a daily basis will help your own writing improve tremendously. i also liked the suggestions of visiting your writing lab or practicing your writing and having someone look over it to give you constructive criticism.
although it is definitely helpful to read books from the literary cannon to expand your reading comprehension skills and vocabulary, i would say that if those authors or books don't interest you and you can't keep yourself interested, don't read them. there are plenty of well-written contemporary books that you can read that will still help you improve your writing skills merely by helping you see good sentence structure and grammar and give you practice with the fluidity of the written word. i would say reading anything, be it john grisham or marie claire (actually has some decent articles for the type of magazine it is!) or harry potter, etc. will help you. and it will be that much better if you are actually interested in reading it and understanding it!