For clarity and style, Joseph M. Williams's book Style gave me a ton of guidance and confidence. It helped me to attend to readers' expectations, and to evaluate my style choices (word selection, word order, paragraph structure) from that perspective.
For how to write a good scene, I learned most from Dwight V. Swain's Techniques of the Selling Writer. Swain's methods are (as he admits) heavily formulaic, but you can easily apply his ideas in a more organic way.
And most of all my local Sacramento writers' group WordForge. Almost all are very good writers, and a growing number are better than very good. They give me encouragement, on-target feedback, and friendship.
Dale