The Elements of Style by Strunk and White. Want to know everything about the mechanics of writing? There is an etiquette, believe it or not, and these guys wrote the Bible on it. The link provided refers you to a free Web edition on Bartleby.com.
Writing Down the Bones by Natalie Goldberg. This tome talks about process process process. Creative writers definitely need to thumb through these pages.
What It Is by Lynda Barry. A great tool to engage your right brain, for writing begins in the imagination. Here’s a cool site to learn more about Lynda: http://www.marlysmagazine.com/
The Penguin Dictionary of Symbols. I don’t know why, but every time I get stuck for something to write about, I pick up my bedragled copy of this book and read away. Somehow it unlocks my mind. That anyone would read what I write after reading the book is another story altogether.
