A writer must avoid shifting your point of view. A verb must agree with their subjects. Foreign words and phrases are not apropos. Watch out for irregular verbs that have creeped into our language. Steer clear of quotations.
Metaphors are like similes.
Be more or less specific. Understatement is always the best. Exaggeration is a billion times worse. The passive voice is to be avoided. Use colloquialisms when pigs fly.