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.
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.