Place yourself in the background; write in a way that comes naturally; work from a suitable design; write with nouns and verbs; do not overwrite; do not overstate; avoid the use of qualifiers; do not affect a breezy style; use orthodox spelling; do not explain too much; avoid fancy words; do not take shortcuts as the cost of clarity; prefer the standard to the offbeat; make sure the reader knows who is speaking; do not use dialect; revise and rewrite.
In a free country it is the duty of writers to pay no attention to duty. Only under a dictatorship is literature expected to exhibit an harmonious design or an inspirational tone.