Recently in my writing I've started to use semi-colons more often. I tend to use them to prevent run-on sentances when I've already used commas and don't want to overuse them, but I know there's more to the semi-colon, so I've come here for some clarification advice.

The colon is to set off a list: pink, purple, white and red. (rose colors, don't ask why I chose those four, I wouldn't be able to give an answer)

The comma is to seperate thoughts, without using a period to do so.

So what is the semi-colon for? Other than to sit underneath the pinky finger of a 'home row' typist and get in the way?

I believe I can help you there, though I don't use the semi-colon all that much myself. Usually, I use a - instead. But that's just me. Anyway... the semi-colon has several uses, some of which I can explain.

1. For seperating ideas in the same sentence, and thereby preventing run-ons.

Ex: Bob went out for dinner that night; however, he couldn't have known what would happen.

2. It's used in lists, like if you are grouping a few items in a list, and then are grouping that group with other groups in another list.

Ex: Things to do today include sweeping, which is a boring task, naturally; laundry, which takes forever; and cleaning my room.

Those are the only two uses I can think of at the moment, but I hope it helps.

I use a semi-colon to join two sentences together, instead of using a comma and a conjunction.

Edit: I guess Locke's first point would be what I'm trying to say here, I suppose. x_x
But I don't think you can substitute -- for ; and also, be careful of using dashes in your writing, because in my writing class I get in trouble for using too many dashes. (: Apparently there isn't a lot of grammatical use for them, and you aren't supposed to use them a lot.

Oh but they make everything so suspenseful and dramatic <3. I love dashes.
'nd for the sake of staying on topic. I guess what Chase and Locke says is correct. I'm personally more of an instinctive grammar user. I have no idea how the rules actually work, and personally am too lazy to find out. Thankfully my instincts tend to get me by (I didn't pay attention in elementary school when it came to sentence structure and grammar D:').

Well, you've come to the right place. You see, semicolons and I have a long, intricate history together; a history riddled with their overuse.

Semicolons are, first and foremost, for those situations where you kinda-sorta-maybe want to start a new sentence, but the two ideas can still be held into one. AKA, they're wonderful for accidentally causing run-ons. Most of the time, their use is purely optional, and just starting another sentence would be perfectly acceptable; however, there are some times where it makes more sense to hold the sentence together. It's definitely not a good idea to overuse them, though; enough people don't fully understand their meaning that it's not worth confusing your readers by throwing around fancy punctuation.

Quite often - but not always - people use an ellipse (...) where a semicolon might be more appropriate:

I thought about it for a while... then, the answer struck me.
vs
I thought about it for a while; then the answer struck me.

If anything, in my mind at least, it conveys a sort of abruptness; the idea following the semicolon is so importantly connected to the idea before that it must be in the same sentence, but has enough importance on its own to be emphasized and separated in some form.

Once again, I state: it's quite often regarded as nothing more than a run-on generator. You've got to be very careful when using it, or else you could go on for half a page with a single sentence. A good rule of thumb is never more than one per sentence, or paragraph, for that matter.

The exception is when using a semicolon to separate out a list; that is, when the individual items in the list contain commas of their own, and trying to separate them otherwise would cause confusion. For example:

Sarah brought along her dad, Fred; her mom, Annie; her brother, Doug; and their dog, Sparky.

If there were only commas there, the sentence would flow very awkwardly, and it would take a couple reads to realize that her dad and Fred were the same person, and so on down the list. In this case, semicolons provide a clear dividing line between each item.

For a slightly more professional explanation: http://en.wikipedia.org/wiki/Semicolon

And yet again I'm struck with having figured that one out more or less on my own, apply it accordingly and never really been able to explain why I use it right and why it is right in the first place.

On the other hand, I have started using semi-colons only recently in the writing of my stories, also using '--' here and there and the omnipresent '...'

Personally, I think '... ' should only be used to indicate a longer pause between things, though it can be that it comes down to semi-colons when it's about a general thought.

For instance:

Whether it was for the better… that remained to be seen.

And is '--' also part of the semi-colon thing? I only apply '--' when there is something of a thought within a thought that commas would make it a little too messy. Rather, the '--' is used to put something in between that isn't necessarily important for the sentence, but rather something of a character's personal side-note.

For instance:

Taking it in stride, he put her down after a while, digging up a ration, changing their source of light – that with some remorse as she did look quite spectacular dressed in bands of light – and making everything ready to go.