Some of you will have seen this Guardian article recommending enjoyable books to read on writing, but I can think of a couple more:
What I like in such books is not just practical advice, but someone who gives me encouragement.
For this, I recommend Walter Mosley’s This Year You Write Your Novel. It’s a mere 103 pages, readable in a few hours, but it contains reassuring and common sense advice that any writer could benefit from, even though it’s aimed at debut authors.
Any of Noah Lukeman’s books on writing is worth the asking price.
Incidentally, Strunk & White’s Elements of Style is widely recommended, but bear in mind that it was first published 100 years ago and revised in 1959, making its advice formal and dated. It still holds good advice, especially about concision.
It is available as a free download in several places, but Project Gutenberg offers the widest choice of file types: