(The best style of writing is) that of the spiritually joyful, luminous and honest man who has overcome his passions. This will be the teaching that there exists a best style: the style corresponding to the good man. (From Human, All Too Human II §88)
“Toward the Teaching of Style.” a note to Lou Salomé written in 1882
Of prime necessity is life: a style should live.
Style should be suited to the specific person with whom you wish to communicate. (The law of mutual relation.)
First, one must determine precisely “what-and-what do I wish to say and present,” before you may write. Writing must be mimicry.
Since the writer lacks many of the speaker’s means, he must in general have for his model a very expressive kind of presentation of necessity, the written copy will appear much paler.
Be careful with periods! Only those people who also have a long duration of breath while speaking are entitled to periods. For most people, the period is a matter of affectation.
Style ought to prove that one believes in an idea; not only that one thinks it but also feels it.
The more abstract a truth which one wishes to teach, the more one must first entice the senses.
Strategy on the part of the good writer of prose consists of choosing his means for stepping close to poetry but never stepping into it.
It is not good manners or clever to deprive one’s reader of the most obvious objections. It is very good manners and very clever to leave it to one’s reader alone to pronounce the ultimate quintessence of our wisdom.
The richness of life reveals itself through a richness of gestures. One must learn to feel everything — the length and retarding of sentences, interpunctuations, the choice of words, the pausing, the sequence of arguments — like gestures.
Form and content are inseparable.
Improving one's thoughts.— To improve one's style — means to improve one's thoughts and nothing else! — If you do not straightaway agree with this it will be impossible to convince you of it. (From Human, All Too Human 'The Wanderer and His Shadow' §131)
Free your prose from resentment.
Teaching of the best style.— The teaching of style can on the one hand be the teaching that one ought to discover the means of expression by virtue of which every state of mind can be conveyed to the reader or auditor; on the other hand, it can be the teaching that one ought to discover the means of expression for the most desirable state of mind, the state, that is to say, which it is most desirable should be communicated and conveyed: that of the spiritually joyful, luminous and honest man who has overcome his passions. This will be the teaching that there exists a best style: the style corresponding to the good man. (From Human, All Too Human II §88)
Credit to Reddit users Lebensmaler & essentialsalts for compiling these quotes from Nietzsche.