Usage

Do not split infinitives.

Like things are compared to, unlike things compared with. See also Business.

Historic refers to a landmark contemporary event, historical refers to past history.

Due to / owing to: The collapse of the wall was due to poor workmanship. The wall collapsed owing to poor workmanship.

Singular / plural: The couple is happy. The company plans to expand. (See also Business). The police were at the scene. Liverpool are favourites to win the cup. (See also Sports).

Premier and prime minister are interchangeable, except in Canada and Australia where the heads of government of states, provinces and territories are premiers and the head of the national government prime minister. Queensland Premier Peter Beattie, but Australian Prime Minister John Howard. Quebec Premier Jean Charest, but Canadian Prime Minister Paul Martin.

Use more than instead of "over" when dealing with figures, e.g. More than 50 persons ... Avoid overuse of "approximately", especially when dealing with people. Not "approximately 25 persons", but about, an estimated or some.

The colon leads from the first statement to the second and can be used to introduce a list or complete the thought of the first statement.
The real winner in the election could come from a completely unexpected quarter: fundamentalism.
When preparing for a trip to the west of Ireland, you should remember three things: an umbrella, a good waterproof coat with a hood and a sturdy pair of boots. (Note that fundamentalism and an are in lower case as they do not start a new sentence.)
Note that a colon is only used to introduce a quotation longer than one sentence. If a quotation is one sentence, a comma should be used.
Chirac said, "I do not agree."
Merkel said: "It all depends on the outcome of the talks. If the British alter their position, perhaps we can alter ours."
In a headline the colon can be used to replace "says" to indicate the source of a statement.
Zimbabwe to pull out of UN: minister
Bush: US not leaving Iraq before 2010
Never use a semicolon here.

A semicolon links two balanced statements. A rule of thumb is only use it where you could also use a full stop. The exception to this is in lists (see below).
The sky was black with toxic smoke; local residents were experiencing breathing problems.
The semicolon is a stronger break than a comma, but not as strong as a colon. It can be used to separate items in a list that already contain commas.
The king wanted to achieve three things from the meeting: a new agreement, to replace the one from 2001, on financing the royal house; a greater awareness of political - and also social - developments in the country; and to confirm the relevance of his office.

The comma usually indicates a natural break in a sentence when spoken. It is used in the following instances:

1. Before a conjunction (and, but, yet etc.) especially if there is a change of subject.
   Porter said that he wanted to take part, but he was not able to do so.
   Jack went up the hill, and Jill followed him.
2. To balance elements.
   The president was not censured, only reprimanded.
3. To prevent ambiguity.
   Hundreds of metres above, the aeroplane circled the airport.
4. For asides (two commas needed here).
   In order to do that, however, he had to climb over the fence.
5. To separate a relative clause that adds extra information but that could be removed from the sentence and not change its meaning (two commas needed here).
   The Kurds, who were able to vote for the first time, did not win the election.
   (Contrast "The Kurds who did vote were disappointed with the results.")
6. After adverbs, phrases and subordinate clauses at the beginning of a sentence (optional).
   Furthermore, the party should ...
   When the final round is finished, the workers ...
   Exception: comma is required after however.
7. To separate words in a list of more than two items (note not before the final "and").
8. For names that appear as extra information and not in apposition (two commas needed).
   The father of the missing child, Martin Smith, was overcome with grief.
   But "Czech President Vaclav Klaus arrived in Germany Thursday."

Dashes can be used to highlight a clause, but remember the style is space-dash-space and only a single dash is used each side of the clause.
The woman - who had arrived on time - could only stare at the departing vehicle.

The tendency in modern writing is to omit commas, semicolons and colons. As much as possible, sentences should be trimmed to three or four lines. Rework longer sentences by taking clauses out and re-writing them as new sentences.

The apostrophe indicates possession or missing letters, as in can't (cannot), didn't (did not) it's (it is) rock 'n' roll, ne'er-do-well.

Singular nouns form the possessive with 's.
The dog's barks woke the child (only one dog).
Note: a proper name ending in s requires only an apostrophe, not another s, as in Charles' coat.

Plural nouns form the possessive with s' except when the plural ends in a letter other than s.
The dogs' barks woke the child (more than one dog).
The women's team, the children's games.

The pronouns his, hers, its, ours, yours, theirs do not need an apostrophe.
The car is yours.
The newspaper did not name its source.

An apostrophe is not required for the plural of abbreviations or in decades:
Five CDs, 10 DVDs, 20 MPs, the 1990s .
It provides clarity in the plural of lower case letters:
Dot your i's and cross your t's (elsewhere, italics could be used here instead of the apostrophe).

The apostrophe is disappearing from company names. Please check company web sites when in doubt.