Great post by Rachelle Gardner recently about the "Writing Rules".
http://www.rachellegardner.com/2011/08/writing-rules-are-just-tools-2 I agree with her so much. We writers sometimes get flooded on "how-to" websites about the "Rules of Writing" that people are afraid to do anything different.
*Active Voice, not Passive
*Avoid Adverbs
*Show don't tell
*Start a story with the hero POV
*Limit the number of POVs
*etc....
On a writing website I frequent (which I refuse to name), they are OBSESSED with the RULES. I see constant posts with titles such as "Is it ok for me to ...?" "Is is ever legal for me to ... ?"
In my opinion, everything is ok to do if the story requires it. When I see such titles my first reaction is always ok if that is the best way to tell your story.
So writer friends, just write. Worry about the rules later.