I'll use this thread solely for all grammar and punctuation-related queries, rather than clutter the board with separate entries on these topics.
In fiction, it depends on the voice I'm going for. If I'm writing an omniscient third-person narrator, I punctuate pretty traditionally. But in first-person, anything goes. I write the way that person would think and speak. Usually with lots of sentence fragments. Like so. I'm more interested in establishing their rhythm in your head, and sometimes that means extraneous commas, just to indicate pauses, like this, or, um … mid-thought ellipses, or I'll use run-on sentences with lots of ands if they're getting excited and worked up and just going on and on and ranting and raving, mechanics be damned. I also like to use dashes in combination with commas to set off phrases in more complex sentences—like an interjection, here—and help clarify the intended pacing for the reader. I don't want them needing to reread a sentence, scratching their head over what I was trying to say because the phrases were grouped in confusing ways; I want them to reread a sentence because it was awesome.
Another thing, if I'm writing lots of characters' dialogue who always tend to clip off their gs, for example, I'll leave off the apostropes at the end throughout, like "He was rantin and ravin alla time" (I often use phonetic spelling like that, too, "n'ah mean?"). Because if you're doing a lot of this, all those apostrophes get really cluttered and annoying on the page. Only in dialogue, I mean, never prose. A lot of people disagree with both of those methods. If that kind of clipped speech is more intermittent, I'll leave the apostrophes in.
