What factor more then any other should affect how and what you write ? why ? ?

Question

need my homwwork done by tomorrow !!! help me !!!!

Answer 1

your personal conviction to the idea, person, place or thing your writing about.  

For a writer to portray an idea, or argument, or persuasion, he must have a conviction/passion to allow his words to convey his feelings on paper.

Answer 2

Your reason or purpose for writing, because that will shape what you write.  If you are writing to entertain, it will be totally different than writing to inform someone of some serious business, or writing a persuasive academic paper, for example.