Grammar
Style guide 
Using hyphens with adverbs
We hyphenate words when they become adjectival in meaning, i.e. they modify the noun that follows them (e.g. 'a long-term plan' but 'in the long term'). But I was taught never to hyphenate words that ended in '-y' or '-ly' as they are adverbial (i.e. they tell us how, why and when). I've recently noticed that newspapers are starting to hyphenate such words, e.g. 'intensively-studied plan'.
Before changing my style, I thought I should do some investigation. I think what Wikipedia has to say on this topic makes sense. It states:
"Hyphens should not normally be used in adverb–adjective modifiers such as wholly owned subsidiary and quickly moving vehicle (because the adverbs clearly modify the adjectives; 'quickly' does not apply to 'vehicle' as 'quickly vehicle' would be meaningless). However, if the adverb can also function as an adjective, then a hyphen may be required for clarity. For example, the phrase more-important reasons ('reasons that are more important') is distinguished from more important reasons ('additional important reasons'), where more is an adjective. ... Other examples are well-received speech and hard-won fight'."
I guess it all comes back to the context.
More grammar tips, grammar e-book and e-newsletter
If you found this tip useful, you might like to read more grammar tips, sign up for the e-newsletter and buy
Other grammar tips include:
apostrophes
colons
em and en rules