Artful Rule-Bending
The best writers bend rules, intently, once he knows them.
... It is an old observation that the best writers sometimes disregard the rules of rhetoric. When they do so, however, the reader will usually find in the sentence some compensating merit, attained at the cost of the violation. Unless he is certain of doing as well, he will probably do best to follow the rules. After he has learned, by their guidance, to write plain English adequate for everyday uses, let him look, for the secrets of style, to the study of the masters of literature.
I have found that it is copywork that best drills rules into your mind.
Once those rules become a part of you, you are at leisure to naturally break them.
Otherwise, your hand has no sense of the underlying creative force that guides it; whatever takes form of your artistic deviations will lack aim, and often be ugly.