Who's rules are you writing by?

I finished (so I hope) two brochures for work today. Several of us had a disagreement regarding whether on-the-hour times should read:

• 8 a.m.
• 8:00 a.m.
• 8:00 A.M.

Now, the first on the list is Associated Press/newspaper style.

Which got me explaining the important of knowing what "style" we wish to convey as an organization and sticking to that style. We also discussed:

• Rev. Dr. Martin Luther King, Jr., celebration
• Rev. Dr. Martin Luther King, Jr. celebration
• Rev. Dr. Martin Luther King Jr. celebration

I felt the insertion of one comma mimicked addressing a person or an envelop, which we're not doing here. I felt no comma was best and two commas felt like creating "Jr." as an appositive phrase that could be removed...

So, who's rules were we trying to follow? Associated Press? Chicago? Etiquette? Our own?

And from there, I pondered who's rules I tried to follow when I write. We must write for ourselves, I've covered that before. But we all impose rules on what we do. First person or third. Third limited or omniscient. Can prepositions end a sentence? Show don't tell.

(Yet, many big commercial authors have no grammar skills and don't follow any rules.)

We want to write by rules of agents and editors. We worry what rules of theme and plot we can break without distancing readers. How much sex is okay?

Last night, my critique group read my new chapter one of Courting Apparitions. They thought it worked, but it raised the following questions:

• Do the frankness of the discussions between the two men, followed by the kissing/greetings rituals of the French make the main character seem bisexual?
• Would a typical American reader lose all sympathy for the main character if it is revealed that he was tricked into sleeping with a 15-year-old girl?
  

The answers were interesting, and made me realize how taboos/rules/expectations of society factor into the rules of writing...