One excellent resource for any student is to study Famous Speeches.

   Abraham Lincoln's   "Gettysburg Address"   or    Martin  Luther King's  "I Have A Dream"  speech  are   powerful demonstrations of   inspired   speaking and Writing.

    Each writer   (I believe)  has his or her own "voice".  There is not just one way to write, just as there is not just one way to think.   Each person   must cultivate their own "voice" by   studying written works and adopting a certain  style of communication.

     You may find some benefit in  learning about the several "voices" which are common to public communication,  such as  Logos,  Ethos, and Pathos.

Sean:

    English is a logical language, and logic  is basic to all Western Conceptions of  "knowledge".

    Therefore,  a  basic knowledge of Logic would be important.

English in that regard, is not so much an issue  with "writing" as it is with "thinking" and how to write in a way that corresponds with how we think.

    The Vocabulary for Written  English   is more expanded than the vocabulary  for spoken English.

     Students who wish to write well in English   are better off avoding the  study of Fictional books and focusing upon  Non-Fiction.

    Some terminology is a   must to be able to  communicate.   By this I mean that you must be able to use certain  words and phrases like a  well-worn tool like a hammer,   saw,  or rule.   This is  like a toolbox that you turn to repeatedly.  One of the ways to accomplish this is to study the written work of certain authors and copy their expressions  and phrasings.