The Elements of Style by William Strunk & E.B. White

The Courage to Write: How Writers Transcend Fear by Ralph Keyes

The Huffington Post Complete Guide to Blogging by the editors of the Post.

Thinking Like Your Editor: How to Write Great Serious Nonfiction–and Get It Published by Alfred Fortunato and Susan Rabiner

The Forest for the Trees: An Editor’s Advice to Writers by Betsy Lerner

The Portable MFA in Creative Writing by The New York Writers Workshop

On Writing Well by William Zinsser

Also check out:

Poets & Writers magazine (www.pw.org)

www.awpwriter.org