PUNCTUATION ISSUES

HOW TO USE COMMAS

Step 1: The listing comma. The most common use of the comma is in place of the word "and" or "or" in a list of words. For instance: “My favorites bands are U2 and Muse and The Cheeky Girls,” sounds clumsy and a bit breathless. Try writing, “My favorite bands are U2, Muse and The Cheeky Girls.”
You shouldn't use the word ‘and' after a listing comma, unless it helps clarify the meaning of a sentence: “My favourite bands are U2, Muse, and Chas and Dave”
In this case, the extra and after the listing comma helps you make it clear you're not a fan of one band called 'Muse and Chas' and another called 'Dave.'

Step 2: The joining comma. A joining comma is used to join two complete sentences together, so that, “You must hand in your essay by Friday.” And, “You will receive a mark of zero.” Becomes: “You must hand in your essay by Friday, or you will receive a mark of zero.” Notice you must use a joining word after a joining comma such as: and, or, but, yet or while. So the following sentence is wrong: “Bangladesh is one of the world's poorest countries, its annual income is only $80 per person.” In this case you should use a semi-colon instead of a comma.

Step 3: The gapping comma. A gapping comma is used to indicate that some words are missing from a sentence. So the sentence, “Some of us wanted to spend the night in a club; others wanted to spend the night in a bar.” Becomes, “Some of us wanted to spend the night in a club; others, in a bar.” The comma after the word 'others' shows that the words "wanted to spend the night" have been taken out.

You can use listing, gapping and joining commas together, for instance:
“Italy is famous for her composers and musicians, (Listing) France, (gapping) for her chefs and philosophers, (joining) and Poland, (gapping) for her logicians and mathematicians.”

Step 4: The bracketing comma. The word comma comes from the Greek for, "a piece cut off", and as the Greeks invented commas, it's safe to say that the bracketing comma is the oldest form of comma ever used.
A pair of bracketing commas is used to indicate a weak interruption that doesn't disrupt the smooth running of the sentence. As in, “She groped for her cigarettes and, finding them, lit one.” Which could also be written as, “She groped for her cigarettes and lit one.” The words within the bracketing commas can be taken out of the sentence without disrupting its meaning. Be careful about this point, as the following example shows, it's easy to get it wrong:
The people in the queue, who managed to get tickets, were very satisfied.
written with commas, this means: 'The people in the queue were very satisfied', when what it's trying to say is:
The people in the queue who managed to get tickets were very satisfied.

If your weak interruption comes at the start or end of a sentence, it is acceptable to use just one bracketing comma: because you cant start or end a sentence with a comma. So the sentence: I think we can say that, all in all, we've done very well.
Could be written as: All in all, I think we can say that we've done very well.
Or:
I think we can say that we've done very well, all in all.

Step 5: Weak interruptions. Though, because, since, after, before, if, when and although are all words that set you up for a weak interruption, like this:
Although I like it here, I am going to have to leave soon.
If you use any of these words at the start of the sentence, it's acceptable to use a comma later on:
Because there's no public transport, I am working from home today.
Note that the final section is a sentence in its own right (I am working from home today), but it is preceded by a qualification.
While it looks the same, this is different to a bracketing comma: you cant take out the section before the comma without changing the meaning of the sentence.

Step 6: The interjecting comma. This is the comma to indicate a pause in the sentence:
Stop, or I'll scream.
You should only really use one interjecting comma in a sentence, otherwise you risk over-punctuating.
Stop, or I'll scream, and shout, at all the people, passing by.

Step 7: Speech commas. Before you use quotation marks, you should insert a comma like this:
She turned round and said, “I don't want to go there.”

HOW TO USE COLONS AND SEMI-COLONS

Step 1: Colon introduction. A colon introduces an explanation or elaboration of what has come before it: like this. To use a colon, you should be satisfied that the two sections of your sentence aren't complete sentences in their own right, and the information in one section explains the other section:
Africa is experiencing a terrible problem: perpetual drought.
Or:
Perpetual drought, poverty, corruption: these are all terrible problems Africa is experiencing.

Step 2: Titles. Colons are also used to separate a book title and sub-title, as in:
Pirates of the Caribbean: Dead mans chest.

Step 3: Ratios. You can use a colon to indicate a ratio, "The man/woman ratio is 1:4!!" In formal writing this isn't normally acceptable. So the sentence would be written as:

There are four women to every man here.

Step 4: Semi-colon introduction. A semi-colon links two complete sentences which work as sentences on their own; it indicates that there is some sort of relationship between them.

Step 5: Stylish semi-colons. Using a semi-colon is always a literary (stylistic) choice, for instance:
It was the best of times; it was the worst of times.
Could also be written as:
It was the best of times, and it was the worst of times.
Or:
It was the best of times. It was the worst of times.

Step 6: Complete sentences. To use a semi-colon, you should be satisfied that the sentences are too closely related to be separated by a full stop, and one sentence isn't a direct explanation of the last.
You can do this in list form too:
1. The sentences are too closely related to be separated by a full stop;
2. One sentence isn't a direct explanation of the last.

Step 7: Marking important breaks. There is one circumstance where you can use semi-colons to break up a very long sentence, to help it be understood. Consider the following sentence:

In Chad, where the famine still continues, western aid workers, in spite of their efforts, are unable to operate, and the people, starving, and desperate, are flooding to refugee camps.

You can use a semi-colon instead of comma to mark the most important breaks in the sentence, just to aid comprehension, like so:

In Chad, where the famine still continues, western aid workers, in spite of their efforts, are unable to operate; and the people, starving, and desperate, are flooding to refugee camps.

Step 8: Joining words. Some words require a semi-colon before their use. It is important to remember though that certain joining words are more appropriate to commas:
Women's conversation is cooperative, while men's is competitive.
Or:
Women's conversation is cooperative; however men's is competitive.
Words like however, thus, therefore, consequently, nevertheless and meanwhile should all be preceded by a semi-colon, while words like and, but, yet and while should be preceded by commas.