In the last few years I've become very interested in art of writing. Below are a collection of random sources I've been learning from.
Constance Hale gets her own section because I love her book, Sin and Syntax: How to Craft Wicked Good Prose. The book is very practical and well organized enough to serve as a reference. Each section includes snippets from some classic authors that provide excellent contextual examples of a given idea she's explaining. It's a book plan to reread several times just to keep all its contents fresh in my head.
I also read her other book, Vex, Hex, Smash, Smooch: Let Verbs Power Your Writing. While I also enjoyed it, it was much drier and didn't provide as much practical information for a novice writer like myself. It has a large section dedicated to specific misused verbs, which was a little too specific for my level but probably appropriate for beginning editors.
In general I found myself agreeing to most of her suggestions. She emphasizes short, to-the-point sentences with strong verbs. Vex, Hex, Smash, Smooch in particular demonstrates the intricacies of verbs in the English language. She has a blog and twitter account where she regularly posts interesting tidbits on writing.