Unity is that property of style which keeps all parts of a sentence in connection with the principal thought and logically subordinate to it. A sentence may be constructed as to suggest the idea of oneness to the mind, or it may be so loosely put together as to produce a confused and indefinite impression. Ideas that have but little connection should be expressed in separate sentences, and not crowded into one.
Keep long parentheses out of the middle of your sentences and when you have apparently brought your sentences to a close don't try to continue the thought or idea by adding supplementary clauses.
STRENGTH
Strength is that property of style which gives animation, energy and vivacity to language and sustains the interest of the reader. It is as necessary to language as good food is to the body. Without it the words are weak and feeble and create little or no impression on the mind. In order to have strength the language must be concise, that is, much expressed in little compass, you must hit the nail fairly on the head and drive it in straight. Go critically over what you write and strike out every word, phrase and clause the omission of which impairs neither the clearness nor force of the sentence and so avoid redundancy, tautology and circumlocution. Give the most important words the most prominent places, which, as has been pointed out elsewhere, are the beginning and end of the sentence.
HARMONY
Harmony is that property of style which gives a smoothness to the sentence, so that when the words are sounded their connection becomes pleasing to the ear. It adapts sound to sense. Most people construct their sentences without giving thought to the way they will sound and as a consequence we have many jarring and discordant combinations such as "Thou strengthenedst thy position and actedst arbitrarily and derogatorily to my interests."
Harsh, disagreeable verbs are liable to occur with the Quaker form Thou of the personal pronoun. This form is now nearly obsolete, the plural you being almost universally used. To obtain harmony in the sentence long words that are hard to pronounce and combinations of letters of one kind should be avoided.
EXPRESSIVE OF WRITER
Style is expressive of the writer, as to who he is and what he is. As a matter of structure in composition it is the indication of what a man can do; as a matter of quality it is an indication of what he is.