Don't use them, even in headlines.
Exceptions:
Follow OD's advice on brackets, copied here below:
There are two main types of brackets.
Round brackets (also called parentheses) are mainly used to separate off information that isn’t essential to the meaning of the rest of the sentence. If you removed the bracketed material the sentence would still make perfectly good sense. For example:
Mount Everest (8848 metres) is the highest mountain in the world.
Use minimal capitalisation. A heading starts with a capital, but other words should not be capped up, unless they are proper nouns. If in doubt, choose lower case.
Exceptions include: our Sun, Earth (the planet), and our Solar System, Universe and Moon, but not other suns, solar systems, universes and moons, or earth as in soil.
Use a capital letter when you are writing the names of people, languages, places and words relating to them:
Use the ellipsis character (… ) in quoted material if you need to show that words have been omitted from the middle of the original quote. In HTML5, it is written: …
The ellipsis should always be followed by a space.
Avoid using them. If the statement is surprising or exciting, it will be clear to the reader without the need for an exclamation mark.
In particular, avoid multiple exclamation marks, e.g.:
…this year the Wildcats are here and full of determination, as never before!!!!
For guidelines on writing in French – for CERN websites and print documents alike – refer to the translation department's "Guide de Typographie".
Too many hyphens make text look cluttered, so avoid them where you can, but they are often necessary to avoid ambiguity. See ndash.
Use a hyphen to join the parts of compound adjectives, for example:
Green-belt land, zero-gravity environment, state-of-the-art phones, well-behaved patients, ill-considered attack, better-trained staff, a little-known city.
Quark–gluon plasma
Lower case, note the en dash
Use double quotes in text, captions, etc. Single quotes for headlines, and quotes within quotes. See quotes.
Do not use quotation marks to soften headlines.
Higgs boson "found" does not mean anything. The quote marks render the headline ambiguous and confuse the reader. Has it been found or not?
CERN physicists spot tantalising hints of Higgs boson is more elegant and gives more information, without the need for quotes.
Readers are entitled to believe that anything appearing within direct quotes are the actual words used by the speaker.
"I really enjoyed the part about the accelerators," says Joe Bloggs. "It got me interested in physics again."
