Instead of using grammar "as rules" for proper usage, we need to use grammar as tools for effective impact.
Grammar Rules are Tools.
That’s right, when it comes to grammar, the rules are tools. Don't think of them as bureaucratic regulations designed to get in your way, and don't think of the chance to bend them as a special treat. Instead, think of them as a collection of techniques that are likely to have the desired effect on your readers.
A corollary: There's no single set of rules. Every style, every genre, has its own guidelines. A Nobel Prize speech demands a different style than an MTV music awards speech (to my knowledge, the former has never included the word “dudes,” nor the latter the word “ineluctable”). Most of the guidelines I lay down here are appropriate for college English papers, a genre calling for a middling degree of formality— that's also roughly the level that most business communication should have. Other styles have other rules, and all you can do is learn what works in what genre.
Keep your audience constantly in mind, and learn to use the rules — even the ones you find silly — to win them over.
The one unbreakable rule: Whatever works works. All that's left for you is to figure out what works. Most of us will spend our lifetimes on that puzzle, and the so-called rules are the closest thing we have to a solution.
We tend to think of grammar as a set of rules for proper writing. Ironically--and despite common perceptions--grammar has little to do with rules in the strict sense of term. Strictly defined, grammar is a comparatively narrow field: Most questions native speakers have about a language deal not with grammar but with usage or style. Grammar is the more scientific aspect of the study of a language: It's made up of morphology (the forms words take, also known as accidence) and syntax (their relation to one another). Grammar gives names to the various parts of speech and their relations (adjectives and adverbs, antecedents, appositions, conjunctions, prepositions, and so on).
So grammar is useful in providing a vocabulary to discuss how language works. But if you're debating whether a sentence sounds overly wordy, or whether language should be concrete, or where to put “only” in a sentence, or when to use italics— strictly speaking--these are all questions of usage and style rather than grammar. And many of these questions come down to nothing more than issues of taste.
Linguists complain that the terms taught in school are inadequate for discussing the way our language really works. It's a fair cop: Most of our grammatical categories are imported from Latin grammar, and often don't jibe well with English. Still, I tend to use the traditional terms, and for two reasons: First, I'm not a linguist, and am not up on the best scientific descriptions of the language; and second, few of my readers were taught the more modern system in school, which means explanations that depended on them would confuse rather than enlighten.
I'm working on a writing guide. It isn't intended to be a formal or systematic grammar, but a guide to effective style. I define grammatical terms only insofar as they're useful in improving usage. If you want real grammar, consider an academic career in linguistics.
One more thing — for the love of Pete, please don't spell it “grammer.”