There are many tips and rules—some which you don't have to adhere to—but this is something which I tell every new writer: do not waste the readers time. I find anyone that doesn't follow this rule usually lacks in many other aspects too.
Everything unnecessary, cut it out. Be it from plot, dialogue, writing style—everything. You see this tip in other forms too, such as write shorter sentences, don't use purple prose, keep it simple and succinct, omit needless words, they all lead back to this fundamental rule: do not waste a readers time.
Vigorous writing is concise. A sentence should contain no unnecessary words, a paragraph no unnecessary sentences, for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts. This requires not that the writer make all his sentences short, or that he avoid all detail and treat his subjects only in outline, but that every word tell.
–William Strunk Jr.
Fifty-nine words, any writer should keep close to heart.
To give an example, "this a subject that" can be reduced to "this subject", "the question as to wether" to "whether", "it's not very big to "small". "That woman is someone who", to "she".
For the love of god, avoid words such as very, the fact that and rather. There are almost no instances where these words are essential for understanding; cut them out, and it leaves the sentence just the same.
If you really wish to learn more, I advise you to read the book "Element of style", by William Strunk Jr. and E.B. White, with about 43 rules, a small treasure books filled with invaluable lessons.
Here are some of my favorites:
6. Do not break sentences in two.
In other words, do not use periods for commas.
I met them on a Cunard liner several years ago. Coming home from Liverpool to New York.
He was an interesting talker. A man who had traveled all over the world, and lived in half a dozen countries.
In both these examples, the first period should be replaced by a comma, and the following word begun with a small letter.
It is permissible to make an emphatic word or expression serve the purpose of a sentence and to punctuate it accordingly:
Again and again he called out. No reply.
The writer must, however, be certain that the emphasis is warranted, and that he will not be suspected of a mere blunder in punctuation.
7. A participial phrase at the beginning of a sentence must refer to the grammatical subject.
Walking slowly down the road, he saw a woman accompanied by two children.
The word walking refers to the subject of the sentence, not to the woman. If the writer wishes to make it refer to the woman, he must recast the sentence:
He saw a woman, accompanied by two children, walking slowly down the road.
Participial phrases preceded by a conjunction or by a preposition, nouns in apposition, adjectives, and adjective phrases come under the same rule if they begin the sentence.
Sometimes, the rules include examples. Keep in mind here, the left is a wrong example, while the right in italic is the correct one.
On arriving in Chicago, his friends met him at the station. When he arrived (or, On his arrival) in Chicago, his friends met him at the station.
A soldier of proved valor, they entrusted him with the defence of the city. A soldier of proved valor, he was entrusted with the defence of the city.
Young and inexperienced, the task seemed easy to me. Young and inexperienced, I thought the task easy.
Without a friend to counsel him, the temptation proved irresistible. Without a friend to counsel him, he found the temptation irresistible.
Sentences violating this rule are often ludicrous.
Being in a dilapidated condition, I was able to buy the house very cheap.
Rule 11. Use the active voice.
The active voice is usually more direct and vigorous than the passive:
I shall always remember my first visit to Boston.
This is much better than
My first visit to Boston will always be remembered by me.
The latter sentence is less direct, less bold, and less concise. If the writer tries
to make it more concise by omitting "by me,"
My first visit to Boston will always be remembered,
it becomes indefinite: is it the writer, or some person undisclosed, or the world at large, that will always remember this visit?
This rule does not, of course, mean that the writer should entirely discard the passive voice, which is frequently convenient and sometimes necessary.
The dramatists of the Restoration are little esteemed to-day.
Modern readers have little esteem for the dramatists of the Restoration.
The first would be the right form in a paragraph on the dramatists of the Restoration; the second, in a paragraph on the tastes of modern readers. The need of making a particular word the subject of the sentence will often, as in these examples, determine which voice is to be used.
Rule 12. Put statements in positive form.
Make definite assertions. Avoid tame, colorless, hesitating, non-committal language. Use the word not as a means of denial or in antithesis, never as a means of evasion.
He was not very often on time. He usually came late.
He did not think that studying Latin was much use. He thought the study of Latin useless.
The Taming of the Shrew is rather weak in spots. Shakespeare does not portray Katharine as a very admirable character, nor does Bianca remain long in memory as an important character in Shakespeare's works. The women in The Taming of the Shrew are unattractive. Katharine is disagreeable, Bianca insignificant.
Rule 15. Express co-ordinate ideas in similar form.
This principle, that of parallel construction, requires that expressions of similar content and function should be outwardly similar. The likeness of form enables the reader to recognize more readily the likeness of content and function.
Familiar instances from the Bible are the Ten Commandments, the Beatitudes, and the petitions of the Lord's Prayer.
The unskilful writer often violates this principle, from a mistaken belief that he should constantly vary the form of his expressions. It is true that in repeating a statement in order to emphasize it he may have need to vary its form (…). But apart from this, he should follow the principle of parallel construction.
Formerly, science was taught by the textbook method, while now the laboratory method is employed. Formerly, science was taught by the textbook method; now it is taught by the laboratory method
The left-hand version gives the impression that the writer is undecided or timid; he seems unable or afraid to choose one form of expression and hold to it. The right-hand version shows that the writer has at least made his choice and abided by it.
By this principle, an article or a preposition (things you put before the noun) applying to all the members of a series must either be used only before the first term or else be repeated before each term.
The French, the Italians, Spanish, and Portuguese. The French, the Italians, the Spanish, and the Portuguese.
In spring, summer, or in winter. In spring, summer, or winter (In spring, in summer, or in winter).
Correlative expressions (both, and; not, but; not only, but also; either, or; first, second, third; and the like) should be followed by the same grammatical construction. Many violations of this rule can be corrected by rearranging the sentence.
It was both a long ceremony and very tedious. The ceremony was both long and tedious.
A time not for words, but action. A time not for words, but for action.
Either you must grant his request or incur his ill will. You must either grant his request or incur his ill will.
My objections are, first, the injustice of the measure; second, that it is unconstitutional. My objections are, first, that the measure is unjust; second, that it is unconstitutional.
And one last tip, a personal one from me—the english language in its punctuation does not only consist of a comma and a period.
We have the em dash '—'
The em dash is perhaps the most versatile punctuation mark. Depending on the context, the em dash can take the place of commas, parentheses, or colons—in each case to slightly different effect.
Use them to seperate thoughts.
And yet, when the car was finally delivered—nearly three months after it was ordered—she decided she no longer wanted it, leaving the dealer with an oddly equipped car that would be difficult to sell.
Use them as a means to summarize.
The document needed a title page, an abstract, a reference page—it needed many things.
We have Parentheses '()'
Parentheses (always used in pairs) allow a writer to provide additional information. The parenthetical material might be a single word, a fragment, or multiple complete sentences.
Use it to add extra tidbits of information.
The president (and his assistant) traveled by private jet.
We verified his law degree (Yale, class of 2002), but his work history remains unconfirmed.
DO NOT use it when it's grammatically integral to the sentence. Meaning, if the sentence can be understood even without parentheses, then it can be used.
The president (and his assistant) were expected to arrive by 10:00 a.m.
We have a semicolon ';'
The semicolon is sometimes described as stronger than a comma but weaker than a period. In certain uses, this is a reasonably accurate definition. Yet there is more to the semicolon than that: the semicolon is used between two independent clauses.
Use it when two seperate sentences can be co-joined into a compound one.
Stevenson's romances are entertaining; they are full of exciting adventures.
It is nearly half past five; we cannot reach town before dark.
Of course, you can also simply use a period too.
Stevenson's romances are entertaining. They are full of exciting adventures.
It is nearly half past five. We cannot reach town before dark.
We have a colon ':'
Use it to list items.
These are the things I need: paper, a pencil and a lot of time.
The school specializes in three subjects: Art, Literature and Science.
We have an exclamation point '!'
I think everybody knows how to use it. I included it on this list, because many don't know how to use it wisely. I think the greatest way to see if a writer cares about his style is by examining the use of exclamation mark.
DO NOT use it more than once.
He screamed, "I hate you!!!"
DO NOT use it as a follow-up to question mark. It is a terminal punctuation (it ends a sentence, subsequently starts a new one and the following letter must be capitalized), and thus stands alone.
What are you doing?!
DO NOT use it in a middle of a sentence. It is still a terminal puntctuation.
"so this is where you went!," he yelled.
DO NOT use it excessively.
I can't give an example for this one, but dial it down with the exclamation points, use it only when absolutely necessary.
Ellipses '…', used to indicate trailing thoughts
I . . . don't know. (yes, that is the correct space/period ratio.)
and tildes '~' used to indicate a drawn out sound
Ouch~
are only used in informal writing. But no one will find fault with you if you do.
I hope this somewhat helped.