I recommend What If: Writing Exercises for Fiction Writers. Yes, that is a textbook for my creative writing class in college, but money well spent and it really helps, as it takes you through the process of fiction writing in expanded detail. Also, if you’re ever into writing poetry, I consider Poetry 180 by Billy Collins to be essential reading.
And if you can stomach the grim memoir of the first half of the book, Steven King’s On Writing is basically invaluable. Kill your darlings. 😛