You must first know the grammar so that when you bend the rules in the name of fiction, you can do so with out being overbearing.

First, the best place for anybody, of any age, to learn not only the rules of grammar and usage but also how to bend and even break them effectly, is in literature. Read books. Lots of them. It's how I learned; I was always so far ahead on this point in my English classes in school that I tended to make my teachers angry.

Second, if the word "but" is a forbidden word in the beginning of sentances, a certain sci-fi author we all know and love is surely sunk! *G*

Shasta

*edit: obviously, good spelling is another matter entirely.

Here are some of the books that I find handy for writing and editing:

• The Chicago Manual of Style: This is the editor's bible. It's nearly impossible to be an editor without knowing this book, and it's incredibly handy for writers, too.
• The Elements of Style: A little outdated, but still full of useful guidelines and tips.
• Merriam-Webster's Dictionary of English Usage: Not sure how to use a word or phrase? This book's got all the answers.
• Style: Ten Lessons in Clarity and Grace: Similar to The Elements of Style, but not so prescriptive.
• The Elements of Editing: A Modern Guide for Editors and Journalists: Another excellent addition to The Elements of Style.
  

The wonky basis is Latin grammar, and the reason it's wonky is that Latin is Latin and English is English.

An example: split infinitives. The traditional rule is that you should never split an infinitive (which means that you never put something between "to" and the verb that goes with it--"to verb" is the infinitive form of the verb). So one of the "blurbs" for STAR TREK breaks this grammar rule because it has "boldly" between the infinitive "to go." ("To boldly go...")

The reason this is a rule in Latin grammar is because Latin infinitives are one word--so you can't put something in the middle. (It would be like trying to put something in the middle of a German infinitive, which is also one word. "To go" in German is "gehen" and how would you put "boldly" in the middle of that? "Gehboldlyen?")

So the rule is wonky because it has a wonky basis.

Other rules are not so wonky. The rule against dangling participles is one. (What, you may ask, is a dangling participle? It's a participle that refers to the wrong object.)

An example of a dangling participle that should make the problem clear:

"Being so awkward in a sentence, I never use dangling participles." ("Being" is the participle, and it dangles because the structure of the sentence indicates that it is referring to "I" when the meaning of the sentence indicates that it is referring to "dangling participles.")

Another example that may not be so clear:

"Running through the forest, the exposed tree roots kept tripping him."

Anyway, the point of all this is to support what Jon Boy said about finding out the reason for the rule and acting accordingly.

Edit: Corrected a typo

I consider myself to be a pretty competent writer, provided I have a computerized spellchecker at hand. There are times when I absolutely must follow the rules of grammar, times when I should bend those rules, and times when anything goes.

Absolute rigid grammar: when I am writing a grant proposal to get a half million dollars from the Federal government, I need to follow the rules to a T.

Bent grammar rules: When I am writing prose, especially in dialogue, I can ofter build a better story by wielding semicolons and sentence fragments like hammers and saws. It's not something I do lightly, and I (hope that I) make a conscious decision to violate grammatical rules before fingers touch keyboard.

Anything goes: When I'm posting messages to Hatrack River Writers Forum, I can boldly split my infinitives. And my friends will understand me even if I begin a sentence with a conjunction. I bet I could even dangle a preposition and you'd still figure out what I was getting at.