I have a thing about correct punctuation, and although I'm aware that most people would find me over-zealous in this regard, I would bring to my defence that it's not just a pointless obsession or a purely aesthetic matter. A bit of poor punctuation will in the best case distract those from the text who notice it and affect their impression of the author, and in the worst case actually give the reader trouble understanding a sentence. Having said that, what I'm going to write about today is more on the aesthetic side, but could nevertheless help you make a good impression on a reader who notices these things.
I have noticed what seems to be a recent trend, especially on the web, to put unnecessary hyphens between adverbs and adjectives when they modify a noun, as in a brightly-lit street (which should be simply a brightly lit street). This habit seems to originate in the hyphenation of compound modifiers, as in real-estate agent or an out-of-date book. But those examples are hyphenated to avoid ambiguity or because the words in that order would not make a valid sentence structure without hyphens. Adverbs that end in -ly are always modifying an adjective or another adverb, so there is no ambiguity. Only adverbs that don't end in -ly, such as well, most or fast should get a hyphen, as in fast-running man.
Here are some examples from sites that I read regularly, including BBC News:
the highly-anticipated device
These should just be:
newly elected councillors
reasonably sized buttons
poorly served areas
the highly anticipated device
After all, you wouldn't write a really-good movie either.
Another trend I've noticed is around the use of dashes in what are called strong interruptions. When you have the right symbols available, there are two ways to punctuate such an interruption:
You can use en-dashes – Option-Minus on a Mac keyboard – surrounded by spaces.
Or you can use the longer em-dashes—Shift-Option-Minus on a Mac keyboard—without spaces.
Using an en-dash with spaces is common in Britain, while using the em-dash is more common in America. Personally I prefer the British style, because it visually offsets the interruption from the rest of the sentence more. What some people tend to use on the web, however, is an em-dash with spaces — like this — which I think looks odd because it creates a huge gap between words. If you prefer the look with spaces, just use an en-dash.
While we're on the topic of dashes, I'll briefly mention two common cases where an en-dash should be used rather than a hyphen. One is for ranges, such as 1980–2008. Another is when combining two nouns in a way that implies a to- or and-relationship, as in the London–Paris Eurostar or parent–child relationship.
My sources for most of this are The Penguin Guide to Punctuation by R. L. Trask and Type and Typography by Phil Baines and Andrew Haslam.