I wonder what's on the shelf next to your desk.
A colleague in an online editors' group initiated a conversation about preferred books on the craft of editing. The first suggestion that popped up was Carol Fisher Saller's succinct and humane The Subversive Copy Editor, an ideal book for a novice and a salutary reminder for the veteran.
Inevitably, I began to think about what I would put on the list.
If you have read a few of the posts at this site, you're aware that not a day goes by without my consulting Merriam-Webster's Dictionary of English Usage and Bryan Garner's Garner's Modern American Usage (third edition). They are indispensable.
The dictionaries nearest to hand are The American Heritage Dictionary of the English Language (fifth edition) and the New Oxford American Dictionary. The fifth edition of Webster's New World College Dictionary is on my desk at The Sun.) I use Merriam-Webster.com online, and if you are flush enough to have subscriptions or lucky enough to have access through a library, the unabridged Merriam-Webster and the Oxford English Dictionary are invaluable for historical and etymological research.
Whatever your house style guide is, you will want to have a copy of The Chicago Manual of Style. It is comprehensive and sensible, and the online question-and-answer service is both informative and entertaining.
When my students are baffled with English Grammar (every semester for twenty years), I have come to recommend Mignon Fogarty's Grammar Girl's Quick and Dirty Tips for Better Writing. Do not cock a snook at Mignon Fogarty because she writes for a popular and less sophisticated audience. She simplifies without oversimplifying, and she advises rather than decreeing. She has a big audience, and she has earned it.
I like Joseph M. Williams's Style: Ten Lessons in Clarity and Grace, which has lucid general statements about writing combined with a wealth of specific examples and exercises.
If you are a trope monger, you will find much to admire in Farnsworth's Classical English Rhetoric by Ward Farnsworth, an elegant book with clear categories and an impressive battery of examples.
Let's run through the standards. I have a reprint of the first edition of H.W. Fowler's Dictionary of Modern English Usage, the 1965 edition revised by Sir Ernest Gowers, and the 1996 edition edited by R.W. Burchfield. I have Theodore M. Bernstein's The Careful Writer and Miss Thistlebottom's Hobgoblins, the latter an invaluable catalogue of superstitions and crotchets, many of which remain current. I have John B. Bremner's Words on Words, which I admire for its certainty and authoritative tone even when I disagree with what he says. All of these are instructive, though you have to deal cautiously with dated advice.
More recently, Bill Walsh's Lapsing into a Comma, The Elephants of Style, and Yes, I Could Care Less will repay your attention.
There is a great deal of nonsense abroad about grammar and usage, and you were likely taught some of it. Robert Lane Greene's You Are What You Speak is a useful corrective for the braying of misguided sticklers. And John McWhorter's The Power of Babel is a good general introduction to the ways linguists see language operating.
For fun, Mary Norris's Between You and Me is a hoot and a half.
There are more, but these should do for a start.
While you are waiting for Amazon.com to deliver, there are also online resources to which I draw your attention: Language Log, the Chronicle of Higher Education's Lingua Franca, Stan Carey's Sentence first and posts at Macmillan Dictionary, and Philip P. Corbett's After deadline posts at The New York Times.
Go for them.