Dialogue on Dialogue

People speak with periods, commas, exclamation points and question marks--they don't use semi-colons, ellipses or dashes (unless they're from an old movie or TV-show like Forbidden Planet, or Star Trek). Read the dialogue out loud first: does it sound like a human, or a research paper?

Next, everyone open your copy of Strunk & White's Elements of Style (Chapter V section 15, page 78 in my copy, the forth edition) for a discussion on accents and dialects. For those without a copy (it's a useful book, only $7 new), you'll have to make do with my thoughts. Webcomics have artwork to show a person's nationality--accurately portraying their speech is thus less important. Trying to emulate a variant of speech in text is taxing on both reader and writer (The reader must distinguish the intended word via the mangled syllables, the writer must be careful to always use the same replacements).

Also important are the visual aspects. If not well-placed, a word-balloon's owner is ambiguous, obscures the artwork, is difficult to read in order and strains the reader. The top is often used for word-balloons with good reasons: it makes them easy to connect to the character's mouth, there is often little of importance draw there and you can space them over the entire width of the frame. Keep them wide to avoid hyphenation. If you have more them one balloon in a frame make sure one is clearly above or farther left than the other.