Back in college, I obtained my second degree black belt in Tae Kwon Do. From the very beginning, Grand Masters Spencer and Cindy Brandt taught the importance of basics.
One of their frequently repeated sayings was: "Perfect practice makes perfect."
This is easily transferred to writing. Using punctuation correctly, with complete sentences, and correct spelling makes for a better piece of writing. Sure, there are rules of grammar that can be broken, but you have to be skilled at the rules of grammar first in order to know how to break them.
If you question something, open a dictionary or grammar book and look it up. Don't rely on the word processing program's dictionary feature to help you out. What if you misspelled the word loose with lose. They're both correct, even though they have different meanings.
Always start with the basics.
Then, once they're perfected, you can move on. But always remember this: a complex piece is only a long set of basic pieces.
A house is a mere set of boards, nails, insulation, and sheetrock (and others) put together in a complex fashion.
The same goes with a book. It's nothing more than a bunch of words, sentences, paragraphs, and chapters put together for a mutual benefit.
Need some assistance with grammar? Check out Grammar Girl for some amazing tips.